FL420 Pulse Oximeter with Alarm

$24.95 24.95

FL420 Fingertip Pulse Oximeter (Blue), Blood Oxygen Monitor with Alarm

The FaceLake FL420 Fingertip Pulse Oximeter quickly measures pulse rate and blood oxygen saturation levels in the body. The FL420 was designed for use by pilots and sports enthusiasts. Pulse rate/SpO2 readings are taken with a swift measurement from the user’s finger. The user’s finger is inserted into the padded interior of the device that was designed to comfortably accommodate a wide variety of finger shapes and sizes.

The FaceLake FL420 Pulse Oximeter with alarm features a custom threshold monitoring system for alerting the user to measurement readings which are outside of the user’s set limits. When enabled, the pulse oximeter speaker emits a beeping sound if a measurement is detected outside the user’s range setting. Alarm preferences are saved in the device’s memory. 

The device clearly displays body activity information on its bright OLED screen. The battery-powered FL420 is suitable for use at home or while traveling. This compact device can be carried in a pocket, backpack, or other small space. The included lanyard allows the user to wear the device around their neck for use while hiking or training. 

This machine is not intended for medical use. The FL420 is recommended for sports and aviation activities such as mountain climbing, biking, or piloting through high elevation areas. The FL420 meets all criteria of CE and FDA standards for pulse oximeters. Measurement readings are taken in under 10 seconds. The FaceLake FL420 Pulse Oximeter is a painless solution for monitoring health activity in the body.

Warranty icon   This unit comes with a 30 day money back guarantee and a one year warranty.


  • Measures oxygen saturation and pulse rate
  • 30+ hours of continuous monitoring on one set of batteries
  • Integrated SpO2 probe and processing display module
  • SpO2 and Pulse Rate bar graph
  • Bright OLED screen displays in full color with sharp text and images
  • Low battery level indication
  • Auto power off after 5 seconds
  • Low power consumption on 2 AAA batteries
  • Interference resistance against ambient light & measurement performance at low perfusion
  • Intended use for spot check of blood oxygen levels at home or in sport/recreational use such as mountain climbing, high-altitude activities, and running
  • Custom alarms for SpO2 and Pulse Rate thresholds
  • Multi-directional display automatically rotates and can be clearly read from multiple viewing angles
  • Accurate sensor measures within ±2% or ±2bpm


Package Includes

  1. FL420 Unit
  2. Instruction Manual
  3. 2 AAA Batteries
  4. Carrying Case
  5. Lanyard

Extended Specifications:

SpO2: Digital
SpO2 Range: 0% - 99%
SpO2 Resolution: ±1%
SpO2 Accuracy: ±2% (70-99%), 35% - 70% unspecified
Pulse Rate: Digital
Pulse Rate Range: 30bpm - 240bpm
Measurement Performance in Low Perfusion
Oxyhemoglobin and Pulse value can be shown accurately when pulse-filling rate is 0.5%
Low battery indicator
Battery Type: AAA Alkaline batteries
Operation Time: 30 hours for normal operation
Interference Resistance Capacity Against Ambient Light
Deviation is smaller than ±1% between value of Oxyhemoglobin measured in natural lighting indoor condition and present lighting sources and of that measured in dark room
Operating Temperature: 5°C - 40°C
Storage Temperature: -40°C - 60°C
Operating Humidity: 15%RH - 80%RH
Size: 57*31*34mm
Weight: 1.8oz (50g)
Display: Color OLED
Warranty 1 Year

Customer Reviews

Based on 15 reviews
3rd Purchase
Pulse ox
Click here to see or download FL420 Pulse Oximeter User ManualIf the link does not open properly on your desktop or mobile device, please contact us.
  1. SpO2 - Digital
  2. Range: 0%-99%
  3. Resolution: +/-1%
  4. Accuracy: +/-2% (70-99%)
  5. 35%--70%, unspecified
  6. Pulse Rate - Digital
  7. Range: 30-240 BPM
  8. Resolution: +/-1bpm
  9. Accuracy: +/-2bpm
  10. Measurement Performance in Low Perfusion
  11. Oxyhemoglobin and Pulse value can be shown accurately when pulse-filling rate is 0.5%
  12. Low battery indicator
  13. Battery Type: 2 AAA Alkaline batteries
  14. Operation time: 30 hours for normal operation
  15. Interference Resistance Capacity Against Ambient Light
  16. Deviation is smaller than +/-1% between value of Oxyhemoglobin measured in natural lighting indoor condition and present lighting sources and of that measured in dark room.
  17. Operating Temperature: 5C-40C
  18. Storage Temperature: -40C - 60C
  19. Operating humidity: 15%RH-80%RH
  20. Storage Humidity:10%RH-95%RH
  21. Size: 57*31*34mm
  22. Weight: 1.8oz(50g)
  23. Display: Bright Red LED

To receive accurate readings, please follow these tips:

  1. Low blood perfusion can affect accuracy of your readings. Warm your hands and fingers before taking your measurements by rubbing your hands together. Remember your pulse oximeter is measuring your SpO2 and PR based on your blood flow. If the blood flow in your finger drops below a certain level, the pulse oximeter will not be able to function.
  2. It usually takes 10 seconds to get accurate readings. Some persons may require a longer time. You may have to wait about 30 seconds for the stable readings.
  3. Keep your hand still while taking a reading - any movement can cause the inaccurate readings.
  4. Nail polish and fake fingernails may cause false readings. If possible, switch to an unpolished nail or consider another application site.
  5. Some medical conditions like atrial fibrillation (afib) and hypotension can result in inaccurate readings. We suggest that you consult a physician before use.

I have installed new batteries but the device still does not turn on. What could be the problem?

The battery placement for oximeters is different from others. Even though the two springs are on the same side, the two batteries are still required to be installed in opposite directions. The diagram shows correct batteries placement. One product image shows the batteries' installation.  If your device still does not work, Please contact the manufacturer to receive a free replacement.

Does it measure the heart rate?
Yes, this device would measure heart rate along with blood oxygen levels.

Are Facelake pulse oximeters latex free?
Yes, Our pulse oximeters are latex free. The hypoallergenic finger chamber is made of medical grade silicone. 

Does this pulse oximeter have an alarm?
No, This pulse oximeter does not have alarm, Our FL100 pulse oximeter has an alarm.

Does this product ever need recalibration?
The finger pulse oximeter does not need any calibration. However, if you have any issues with the device, please check the user manual and Precaution or contact us. We will be more than happy to further assist.

What kind of battery does the Facelake pulse oximeter use?
The Facelake fingertip pulse oximeter uses 2x AAA alkaline batteries.

Can I use your facelake pulse oximeter during sleep?
This pulse oximeter can not be used for continuous monitoring, and it does not have a memory to save the readings. It will give you a reading as long as you have your finger inside the finger chamber but . Once you take your finger out, the pulse oximeter will turn off after 5 seconds.