CMS 50-DL Fingertip Pulse Oximeter Review – Better Than Zacurate?

The Contec CMS 50-DL Pulse Oximeter measures SpO2 and pulse rate in 8 seconds, has a 12-month warranty, and over 5,000 reviews on Amazon.

Accurately monitoring your blood oxygen levels using pulse oximetry can be useful for a range of physical activities, such as hiking or cycling.

But how accurate is the CMS 50-DL Oximeter, and is it worth buying?

In this review, we’ll guide you through the design features, customer feedback, warranty coverage, and how to achieve the most accurate readings.

We’ve also included comparisons with similar devices, to help you decide if this is the best fingertip pulse oximeter for you.

Design Features

CMS 50-DL Fingertip Pulse Oximeter

As one of the cheapest and most popular oximeters on Amazon, the CMS 50-DL has thousands of positive reviews. The bright LED can clearly display your Sp02 and pulse in under 8 seconds, and the 45 degree spring hinge adjusts to fit any adult finger.

But because of the price, you’re not getting most of the advanced features, such as a plethysmograph and auditory limit alarm.

The pleth waveform is useful for ensuring your pulse rate is stable before starting the reading. An auditory alarm can be helpful for identifying when your Sp02 and pulse exceed upper and lower limits.

A few of the best home oximeters that offer both of these features are the Zacurate 500D, Vive Precision Oximeter, and Innovo Deluxe Oximeter.

Each of these three devices also features a multi-directional display, which means you can change which way the results are displayed. With the CMS 50-DL, the LED screen is fixed in one position, facing away from the user.

While this is perfect for caregivers and anyone administering the reading for you, if you’re taking the reading yourself, it can make it more difficult to read the results.

Contec also send you a useful carry case and lanyard, in addition to the batteries and main device. The case helps to protect the oximeter during travel or when it’s not in use, with the lanyard making it easier to keep the device nearby if you need to take readings throughout the day.

Of the 3 other pulse oximeters we mentioned above, the Vive Precision device is the only one that also includes a lanyard and carry case.

How is it Powered?

The CMS 50-DL Oximeter is powered by 2 x AAA batteries, providing up to 30-hours of use. A low battery indicator on the display screen helps to ensure the accuracy of your pulse and Sp02 readings is never impacted by a lack of power.

Having to rely on batteries is a little frustrating, but there’s no way to charge using an AC adapter or USB cable.

A pack of 8 rechargeable AAA batteries should set you back no more than $10-$12, which could help save you money in the long run. Contec have also built-in a 5-second power-off feature, which helps preserve battery life when not in use.

There’s a few oximeters on the market that offer alternative power sources, such as via phone cable or USB. Some, like Masimo iSp02, can connect straight to an Apple iOS device without the need for batteries, making them incredibly lightweight.

But some customers have reported connectivity issues with such devices, which generally makes them less reliable than battery-powered oximeters, like the CMS 50-DL.

CMS 50-DL Fingertip Pulse Oximeter

CMS 50-DL Oximeter – Product Summary

  • Accurately determines your SpO2 and pulse rate in less than 8 seconds
  • 45 degree adjustable spring hinge adjusts to fit any adult sized finger
  • SP02 Accuracy is +- 2% (70-99%) Pulse Rate Accuracy is +- 2 bpm
  • Bright LED display allows easy viewing in dark surroundings or bright sunlight
  • High quality silicon probe is completely hypoallergenic and latex free
  • Quick and reliable oxygen saturation readings – perfect for aviators, sporting enthusiasts, skiers, bikers or high altitude climbing
  • Quick snap-off cover for easy battery removal
  • Automatic shut off after 5 seconds to save battery life
  • Includes 2 x AAA batteries, pulse oximeter case, and lanyard
  • FDA approved oximeter
  • 1-year manufacturer’s warranty

Accuracy and Ease of Use

Tips for Accurate Pulse Oximetry

The most common reasons customers gave for lower review ratings on Amazon relate to accuracy.

That’s why we’ve added a quick guide for how to achieve the most accurate Sp02 and pulse readings with the CMS 50-DL Oximeter.

  1. Ensure batteries are installed correctly
  2. Open the clamp
  3. Insert finger into the clip, with your fingernail facing upwards towards the screen
  4. Ensure your fingertip is directly in between the LED light source and LED sensor
  5. Release the clamp
  6. Press the button on front of the device once
  7. Keep finger and body still while the oximeter is taking its readings

What Should You Avoid?

Poor blood circulation can cause inaccurate or results. Warm your hands and fingers before taking the reading to increase blood flow.

The World Health Organisation (WHO) has also advised against wearing nail varnish or allowing bright light to enter the sensor. The color from nail varnish can absorb light from the oximeter and interfere with detection of oxygenated haemoglobin.

Certain medical conditions can also affect the accuracy of pulse oximetry. If you have hypotension, anaemia, tachycardia, hypothermia, or bradycardia, we recommend seeking advice from your physician.

A recent scientific study has shown that the highest Sp02 tends to be in the middle finger of the right hand. Conversely, the lowest is in the middle finger of the left hand, which is why we recommend using the same finger each time.


  • 1 year

Who Are Contec Medical Systems?

Contec Medical Systems (CMS) was founded in 1996 as a tech company focussed on delivering high quality medical devices. Today, their product line has expanded to include ECG machines, sphygmomanometers, ultrasound equipment, and EEG, in addition to their pulse oximeters.

CMS are based in Qinhuangdao, a port city on the coast of China in northeastern Hebei province. Their products have passed CE and FDA guidelines, and they currently distribute more than 2 million products each year to over 200 countries and regions.

What Do Other Reviews Say?

Our own oximeter reviews provide you with in-depth information and comparisons between the best devices.

But it’s also useful to check the feedback from as many people as possible, as not everyone has the same experience.

How easy was it to take a reading? Was customer service helpful and easy to contact? Were the readings accurate, and how comfortable was the fingertip grip?

The problem is, the best oximeters have thousands of reviews, and finding the most valuable information can be time consuming.

That’s why we did the leg work for you.

Listed below you’ll find a summary of the pros and cons for the CMS 50-DL Oximeter, based on direct customer feedback.


  • Great value for money – one of the cheapest oximeters on the market
  • Excellent correlation between this and expensive medical units, at high (97-100% saturation), mid range, and low range (to 83% saturation), according to a medical professional that bought and used the device
  • Carry case helps protect the CMS 50-DL when not in use
  • Quick and easy to use
  • Self-power down helps to prolong the battery life
  • Produced by a company that specialize in electronic medical equipment, which also includes nebulizers and ECG machines
  • Provides a useful indication for when to use a nebulizer for anyone with asthma
  • Results are available quickly – in just 4 – 7 seconds according to some reviews
  • Clamp is firm enough to stay secure but without pinching your finger
  • Highly durable construction
  • Large number of reviews report the accuracy is comparable with devices customers used in hospitals
  • Lightweight and easy to carry


  • No way to rotate the display, although readings can still be seen upright when your finger is folded in towards your palm
  • If you have cold hands or move and cause the reading to take longer, the auto power-off feature can activate
  • Not necessarily a con, but a feature worth noting. The springs in the battery compartment don’t tally with the polarity markings. This means you have to insert the batteries the opposite way round to what you might expect.
  • Cannot display a plethysmograph for waveform analysis, although this is to be expected given the price
  • Lanyard material is not particularly high quality
Oximeter Buying Guide

CMS 50-DL Review Summary

Overall Review Rating

4 / 5

So, is the CMS 50-DL Oximeter worth buying?

After comparing it to most of the top finger pulse oximeters on the market, it's certainly one of the cheapest. But if you're willing to spend a few extra dollars, there are some much better devices out there.

With the CMS 50-DL, you have no plethysmograph, alarm settings, or rotating display, and the results face away from you with a spread palm.

For what's usually an extra $6-$7, you could buy an oximeter with all of these features, in the form of the Zacurate 500 DL.

Both Zacurate (Med Shop and Beyond) and Contec Medical Systems (CMS) have US-based contact numbers, street addresses and email addresses, so contacting either company shouldn't be a problem, should you need support.

If you're on a tight budget and literally only need to know blood oxygen saturation (Sp02) and pulse rate, the CMS-50DL is your best option.

But if you can afford to upgrade to the Zacurate 500DL, you'll enjoy a better user experience with the rotating display, and the potential for more accurate readings with the pleth waveform.

Leave a Reply

Your email address will not be published. Required fields are marked *