Review on FACEIL Digital Pulse Oximeter Fingertip Blood Oxygen Saturation Monitor With LED Display, Fast Spo2 Level Reading Heart Rate And Perfusion Index - Includes Lanyard & Batteries by Jeff Langford

This product does exactly what it says it does! I tried comparing the heart rate it showed to the one tracked by my apple watch and they were almost identical. It comes with 2 triple A Batteries, and the screen notifies you of the battery level, but make sure you have additional batteries on hand for when it eventually dies. I have not had any issues with battery life, because it automatically turns off after a few second of not being used, which is pretty nice. Overall, it is a great product for the price you are paying. It is easy to use, accurate, and overall worth it.