Contec CMS50DL Oximeter – New Stock

Our latest batch of Contec CMS50DL oximeters now comes with blue protective casing, batteries and lanyard. We have updated our listing accordingly.

As a result of improved GBP to USD change rates, we have also been able to reduce our pricing by £5 per oximeter.


Our price transparency promise

We buy only genuine Contec Medical oximeters. As such, we pay a lot more for our oximeters than companies importing ‘copycat’ fakes. We’re also an established VAT-registered company – not a short-term pop-up seller – which increases our pricing to the end user by 20%.

Throughout the pandemic, we have been firmly committed to charging fair prices on our oximeters. Our pricing and our margins have fluctuated with changing pricing from the manufacturer, global shipping price fluctuations, and exchange rate variations. If you are from an NHS or other registered medical organisation and would like to see our costs in sourcing these oximeters, please get in touch. We are very happy to share copies of our invoices from the European sales manager at Contec, as well as exchange rates paid on the day, so that you can prove due diligence and know that we are charging a very fair price for these products.




Recent Amazon reviews on the fake CMS50DLs they are promoting:

Contec CMS50DL one of only two low cost oximeters to meet accuracy standards

In a paper published in the journal ‘Anesthesia and Analgesia,’ only two low cost oximeters were found to meet FDA accuracy standards, and the Contec CMS50DL was one of them. The authors concluded that “Many low-cost pulse oximeters sold to consumers demonstrate highly inaccurate readings. Unexpectedly, the accuracy of some low-cost pulse oximeters tested here performed similarly to more expensive, ISO-cleared units when measuring hypoxia in healthy subjects.”

You can read the full article here: The Accuracy of 6 Inexpensive Pulse Oximeters Not Cleared by… : Anesthesia & Analgesia (

Our response to BBC’s article on pulse oximeters today

Hello BBC,

I am a researcher at Imperial College, and a small business owner. This is not the first time I have emailed you on the topic of your reporting with regard to pulse oximeters. Now I see yet another article from the BBC persuading people to rush out and buy pulse oximeters, with very little guidance (except “check it has the CE kitemark”):

The £20 pricetag is very misleading. Genuine Contec pulse oximeters, for example – generally the cheapest of the legitimate, properly tested ones – cost a distributor more than £20. Add shipping and import VAT onto that, not to mention transaction fees and UK delivery costs, and there’s absolutely no way anybody can sell a safe, genuine pulse oximeter for £20. Back in February 2020? Yes, sure. But since April 2020, when manufacturers tripled their pricing? Absolutely no way.

Advising readers that they can purchase a pulse oximeter for £20 is dangerous. It drives them to buy from unscrupulous, opportunistic profiteering sellers, with no medical background whatsoever, who have been shipping in copycat/fake oximeters that cost them about $3 apiece. Advising people to check for a CE mark is of no help whatsoever. It’s well known that fake CE marks have been pouring out of factories in China.

Your article will line the pockets of criminals and equip thousands of people in the UK with untested devices which they will trust for guidance but which, rather than “save lives,” cost them.


Britons spending thousands of pounds on counterfeit and unsafe medical devices during the COVID-19 pandemic

A customer recently drew my attention to articles from various credible sources (including Tatler and The Guardian) about ‘must have’ medical devices for the home, in the context of Coronavirus. These articles are very well-meaning, but I feel they should come with proper guidance.


When the Coronavirus pandemic hit us in the UK, our business saw a surge in sales of devices such as pulse oximeters. Unfortunately, however, this surge in demand did not go unnoticed from opportunists, and within a few weeks, anyone with a website and/or eBay account was stocked up with pulse oximeters. The vast majority of these are fakes, produced by factories who create counterfeit versions of the popular Contec Medical CMS50DL. They are made to look almost identical and are often advertised by unscrupulous sellers as the genuine thing, but they have no CE certificate and with nobody checking their accuracy levels, are potentially not even fit for purpose. Unfortunately, HMRC never seems to find and stop these devices from coming into the country. They are supplied from China at only $8 apiece, and sold by companies with absolutely no expertise in medical products for a massive markup – around £20-25 each.


We simply cannot compete with this pricing (even our factory pricing is nowhere close to what they can sell for, retail), and inevitably, demand has greatly reduced, as the vast majority of people seeking pulse oximeters get directed to listings of counterfeit devices. The manufacturer is helping us to report fraudulent listings to sites like eBay, but new ones appear as fast as they’re taken down.


Nearly all the major newspapers and news sites have recommended pulse oximeters for the home, and are inadvertently sending thousands of people off to buy equipment that may prove to be at best ineffective, and at worst misleading and dangerous. These are not simply words from a business that has seen a sudden reduction in sales. These are the words of medical professionals who have worked for years in the NHS. We don’t only have customers, we also have patients, and our patients – cardiac patients – are among the most vulnerable to this disease.


At the very least, people should only buy from websites or listings where it is clear who the manufacturer of the device they are buying is (to prevent them from buying mickey mouse equipment), and which displays some kind of evidence that the seller is an authorised distributor of that company (to prevent them from buying from people claiming their equipment is something it is not).


Our main guidance for buying a pulse oximeter at the present time is as follows:


  • Manufacturer: Know who the manufacturer of the equipment is, and check this against the product you receive. Substandard products will either have made up manufacturer names (so when you search for the name of the manufacturer, you won’t find the manufacturer’s website), or will claim to be something that they are not. The most popular, and therefore most frequently copied pulse oximeter, is the Contec Medical CMS50DL, but often, the product received is called something completely different.
  • Price: Since COVID-19, the cost of genuine medical devices has more than doubled for suppliers. Supply chains have broken down and many manufacturers have had to buy parts from alternative, more expensive sources. While pulse oximeters used to be as cheap as £25, it would be almost impossible – in the present climate – to find a certified product for less than £35, particularly on sites like eBay and Amazon where sellers have to factor in the cost of fees. Unbelievably low pricing should be an instant red flag. For the best genuine deals, try and buy direct from medical companies – not from third party sites like eBay and Amazon.
  • CE Certificate: If in any doubt, ask to see the CE certificate of the device (don’t simply believe product descriptions that claim the device has CE certification). The CE certificate will also list who the true manufacturer is. You could also ask to see a letter of authorisation from the manufacturer, showing that the company selling you the device is an authorised distributor. Here’s ours:




Pulse Oximeters: a simple device in the battle against Covid-19

The advice to anyone displaying symptoms of coronavirus is to self-isolate, treat the symptoms with the like of paracetamol or ibuprofen and, if necessary, contact the NHS 111 telephone number for advice. A high temperature, and a new, continuous cough are the main, but not the only symptoms. The government advises anyone with symptoms to self-isolate until the temperature returns to normal, getting lots of rest and make sure not to get dehydrated. The cough however can continue for some time after the infection is over.

Most people with coronavirus experience only relatively mild symptoms. It is clear however that others experience truly unpleasant symptoms – like the worst flu ever, some have said; like razor blades in my chest, said others – and a small minority have symptoms severe enough that hospital admission becomes necessary. Those who find the virus most problematic often become breathless, as they struggle to get enough oxygen into their blood, and it is this shortness of breath that is often an indication that the sickness may be getting more serious. If not treated, viral pneumonia can result, and we know that the government has been concerned that the NHS could be overwhelmed, with too few ventilators available to save lives.

Writing in The New York Times, (and reported in The Times), New Hampshire doctor, Richard Levitan, explained that “We are just beginning to recognise that Covid pneumonia initially causes a form of oxygen deprivation we call ‘silent hypoxia’ – ‘silent’ because of its insidious, hard-to-detect nature”. The danger comes, he has said, by the fact that people’s brains are working normally, and their body has accommodated what turn out to be scarily low levels of oxygen levels.

The monitoring of blood oxygen levels, to get early warning of problems, has become an important weapon in the fight against the virus. In order for this to happen, Dr Levitan suggests, people could monitor themselves by means of simple technology, called a pulse oximeter. The public, he says, should think of an oximeter, a simple clip put on the finger that measures your oxygen level, in the same way they do a thermometer. And, just as a very high temperature measured by a thermometer would be a spur to call the GP surgery, so low oxygen levels recorded by an oximeter should prompt anyone to seek medical advice. Pulse oximeters, he says, have helped save two friends of his, while in Germany, which has the lowest death rate in Europe, Covid patients are visited each day and their oxygen levels checked.

The report in The Times quotes Professor Babak Javid, consultant in infectious diseases at Cambridge University Hospitals, who says that “Many of the features of Covid are strikingly reminiscent of other lung infections that interfere with the ability of the lungs to oxygenate the blood”. This may not be apparent in previously fit people, so the pulse oximeter is best used in such instances after mild exercise. Even walking for a few minutes would place enough demand for oxygen from the lungs that blood oxygen levels fall dramatically.

Through all of this, Dr Levitan remains hopeful, telling CBS News: “What we are learning about this disease is it attacks primarily through one pathway, and that’s the lungs. We know when it is going to attack. It is going to attack between five to 10 days after infection. … And we know we have a way to detect it earlier, and that way is by close monitoring of pulse oximetry.”

Lessons of COVID19: Buy direct from UK companies

How Amazon weakens domestic businesses – and leaves us unable to meet Coronavirus demand

In May last year, a customer who purchased a CMS60D pulse oximeter made a false complaint against our company. We’d sold hundreds of these oximeters over the years, and had 5* reviews on every purchase. This one person claimed – without getting in touch with us first – that we’d sent him a used item, sold as new.

Without attempting to verify this, Amazon immediately pulled down our listing, cutting off a huge portion of cash flow to our company (this was our best selling product), and leaving us sitting on a large amount of stock. What’s more, they left UK customers with no domestic supplier – their only option to order from sellers in China who have no ability to support the product whatsoever (they are not medical professionals!).

There was nobody we could even contact about this. Despite the hundreds of pounds in fees Amazon charge us each month, the only phone contact is a call centre based in India, staffed by people who cannot help. Emails are answered by people who copy and paste generic responses, frequently investing so little time in reading your email, they don’t even check what language you wrote it in before sending back a standard response in German or Spanish. Writing to Jeff Bezos also gets you palmed off to India. The fight to clear our name took 9 months and more hours than we dare count, and in the end was only successful out of sheer serendipity – that, in the line of my work in the NHS, I met somebody who worked high up the Amazon food chain and who was willing to help.

The worst part is, we now know we’re only one negative feedback away from it happening all over again. When you supply over 900 customers every year, you’re statistically pretty likely to encounter one unreasonable or dishonest one at some point.


The cost to our business

The estimated loss of cash flow to our business was £18,000 over this period, and overall means that the business is currently operating at a loss. Amazon effectively became judge and jury of our business, in a field they know absolutely nothing about (healthcare). This is something they do all the time to businesses in the UK – just search Google and you’ll get hundreds of similar stories of businesses that have closed down because Amazon, without legitimate reason, have pulled products they’ve spent years building up the profile of in the Amazon marketplace. Often these are craft businesses, run by entrepreneurs who are carers for disabled relatives and have come up with a way of generating some extra income from home and slowly built their profile through years of hard work and great customer service. They have built Amazon’s fortunes along the way by using Amazon as their marketplace, but then their entire livelihoods are cut off, without warning – just like that.

Businesses are practically forced to sell through Amazon nowadays, because so many people use it as their default shopping portal. People don’t seek out companies directly any more, and they can’t be bothered to fill in their details at checkout with a company they’ve not used before when, with Amazon, it’s already saved and can be done in a single click.

By the time our ability to sell was finally reinstated in December 2019, we’d begun to run low on other medical devices, but we were unable to reorder because so much of our cash was tied up in the stock Amazon had banned us from selling. Our order sizes had to shrink to only 100 or so items at a time. We estimate that our business would recover by around April 2020, and we’d be able to return to our normal ordering cycles and quantities.



Then, Coronavirus hit the UK. Demand for our pulse oximeters soared, but instead of our usual buffer of 200 CMS50DLs, we had 20. Instead of our usual buffer of 200 CMS50E, we had 80. We were running low on neonate and paediatric probes for our CMS60Ds. Contec Medical were unable to take our order because their government had ordered them to produce for domestic hospitals only. The damage Amazon had done to our business in the preceding 9 months meant that we were less prepared than ever before to meet the needs of our clients, at the very time when they needed us the most.

Demand for the products we stock continues to increase on a daily basis from GPs, hospitals, paramedics and even home users. On top of the damage done to our ability to be prepared for this demand by Amazon from last year, marketplaces like Amazon and eBay are shamelessly profiting from this crisis – whilst sending out emails warning sellers not to increase their pricing during this time of crisis, and that punishment awaits anyone who does.  Yet, neither Amazon nor eBay are reducing their fees for sellers of these devices, even as our costs of getting hold of them increase. As well as high selling fees, they also hold onto our funds for weeks, sometimes months – PayPal holds onto 10% of every sale for 3 months – meaning that small businesses are running out of stock but not being given access to their own money with which to reorder. When profit margins are lower than 10% as it is, this missing 10% of capital is severely limiting. It’s the difference, for example, between being able to reorder 1000 more oximeters, or 1100, during this two day window of ordering opportunity before Contec Medical shut down for international orders once again. It’s the difference of 100 more people in the UK being able to get a genuine, safe, UK-supported CMS50DL fingertip pulse oximeter delivered to them within 24 hours, or having to take their chances buying what will likely be an imitation product from China of questionable accuracy – given that all genuine Contec Medical equipment is being directed to Chinese hospitals and not sold to retail customers outside of China.

These next few months will bring up many issues that have been quietly simmering for years: chronic underinvestment in our NHS; the vulnerability of workers who are ‘self employed’ but, in reality, work for a company (such as delivery drivers); our reliance on foreign manufacturing; the failure of HMRC to police imports into our country and prevent tax evasion by foreign sellers, undermining UK businesses who must abide by the law and cannot compete. And, on top of all of these things, the gradual weakening and destruction of domestic businesses by the monopoly and uncontrolled power of huge, exploitative US corporations.

Conveience always comes at a price, and now we are paying it. Please, don’t keep letting Amazon profit from destruction and crisis. Cancel Prime, uninstall your App. Make the extra effort to buy direct from UK businesses, now and forever more, in as many areas of your life as you possibly can. Domestic businesses are the only ones who can be mobilised for their local population at times of crisis, and we need them present and strong.

How Amazon attacked our medical business

Every product we offer at Finger On Pulse, we known inside out. I work in the NHS myself, and I’m regularly on the telephone with doctors or home users, talking them through setting up their new medical device. I know our clients are happy, because they tell me – and on the rare occasion when they aren’t happy, they tell me that, too. That’s because our customers can email or call us at any time, and we have real human beings at the other end to answer them.

If only Amazon knew what customer support was! Last week, I received an email out of the blue to tell me that a customer had anonymously complained that their Contec CMS60D pulse oximeter had arrived in used condition. We quality check and photograph all of our orders prior to dispatch, and we don’t even hold any used stock (on the rare occasion that we receive a return, it goes immediately back to Contec; we don’t hold onto it), so proving that this was a mistake would have been straightforward. Noticing that this was the only such complaint in over three years of Amazon sales would also have been a clue that this was unlikely to be true.

Rather than being given the opportunity to explain this, however, our CMS60D listing was immediately suspended. I was asked to set aside 1-2 hours of my day to put together a detailed plan of how I would prevent such an incident (you know, the one that never actually happened) ever happening again, and also to hand over a bunch of confidential information into the hands of Amazon, such as the last 365 days worth of purchases I have made from our supplier, along with their full contact information. Luckily, Amazon don’t have a reputation for forcing their way into new markets through underhanded methods and have not recently developed an interest in healthcare, so I was more than happy to share all of this information with them (that’s sarcasm, by the way).

But, seriously, I had little choice. It was hand over our invoices, or not be allowed to sell on Amazon any longer. So I prepared a plan to address a hypothetical problem, and sent in my documentation.

I first received a reply in Spanish, telling me that our product could now be relisted, but when I followed the steps (using Google Translate), it would not allow me to publish the listing back. I then received an email in German to tell me that Amazon required more information. I emailed back to ask what was happening, and was then emailed in English:

We received your submission but do not have enough information to reactivate your listings at this time.

Why did I receive this message?
You have not sent us sufficient information that we previously requested from you. We requested this information to address the complaints we received about the condition or description of your items

For privacy reasons, we do not provide details about our investigation methods.

What happens now?
Your listings will remain deactivated and we may not respond to further emails about this issue. If we receive more complaints about your listings, we may deactivate your Amazon seller account.

The information I’ve provided isn’t good enough, they won’t tell me why, and they won’t respond to further emails. Seems like code for “thank you for providing us everything we need to take over this market from you, you have now served your purpose – goodbye.”

I’m sure they will succeed, for a time. Until they realise that their call centres are not equipped to support doctors, nurses, paramedics, or even serious home users with health conditions. Or, more likely, until those people realise Amazon cannot support them, and seek out specialist companies like ours. Until one day, maybe, the world begins to fight back against companies who seek to do business through deceit and destruction, and not by cooperation. I have no intrinsic distrust of monopolies, but only when they are won by genuinely being the best option out there.

Sadly, that world isn’t coming any time soon (in our countries, at least, what power does the British government have to protect anybody’s interests any more?), but I, for one, will be canceling my Prime and Audible subscriptions and publishing my next book through a real publisher. I’ve already been fulfilling a promise to myself, for the past two years, to always seek out the individual seller on marketplaces like Amazon, and go direct wherever possible. Amazon take a huge cut of every sale, and I’d rather that money went to a business based in the UK, employing people living here, paying our taxes, and supporting our communities.

Amazon won’t even notice me go, but it’s time to accelerate my efforts to put ethics before convenience. Lamenting the loss of the high street is one thing, but soon – with the exception of the ultra niche – we’ll be lamenting the loss of any shopping experience at all outside of Amazon.

Oxygen saturation of arterial blood flow

The BBC News published an article which discusses the benefits of new technology which will allow doctors to measure blood pressure from arterial blood flow through the aorta. Arterial blood flow is more important than other types of blood flow (such as deoxygenated vascular blood returning back to the heart) because it has been freshly pumped straight from the heart; this means that it gives a much more accurate picture of blood pressure actually at the heart (and therefore a more accurate picture of your risk of heart disease). This also means, in the case of sp02 measurement, that this recently oxygenated arterial blood can be an accurate indicator of lung function.

All the fingertip pulse oximeters and handheld pulse oximeters at FingerOnPulse.Com measure the pulse rate and sp02 from arterial blood only. The oximeters can cleverly distinguish between arterial blood and other interference (venous blood, bone, muscle, fat and even fingernail polish) by looking out for the tell-tale pulsing rhythm of the arterial blood, as it is pumped straight out from the heart.

When it comes to sp02 measurement, high-quality oximeters look for the differences in absorbance of red and infrared light, caused by the difference in colour between oxygen-bound (bright red) and oxygen-unbound (dark red or even blue) haemoglobin. The percent of haemoglobin molecules bound with oxygen molecules is your oxygenation reading.

What is the waveform display?

Some more advanced fingertip pulse oximeters boast waveform displays as one of their features – but what is really going on?

Pulse Oximeters differentiate between the light absorbed by the oxygenated arterial blood (what it wants to measure), and other interference (light absorbed by veins, skin and bone, for example).

The difference between arterial blood and other blood is that arterial blood is pumped by the heart, pulsing and fading with each heartbeat.

Oximeters subtract trough from peak levels, and the difference is the light absorbed only by the arterial blood. These troughs and peaks are what are being displayed in graphical format on your fingertip pulse oximeter with waveform display capability.