The Pulse Oximeter is included so that you may monitor both your heart rate and your oxygen saturation levels in accordance with the protocols for adaptive contrast training. To use it, put it on your index finger and push the button on the top to activate it when working out to check these stats at a glance. The top number is your oxygen saturation level. On a healthy, active person this will be between 95-97 before you start using the oxygen. As you are using the oxygen this number will likely go up to 99 and when you go into high altitude mode it will probably drop below 91, possibly even to 75.
The bottom number measures your pulse/heart rate. When exercising, a good target is to try and get it up past 120 BPM. When you are on LiveO2 mode (oxygen rich) it will probably be less. When you go into Adaptive Contrast (AC) mode (limited oxygen) it will enable you to get your heart rate up so the number will go higher. Getting your heart rate up when using altitude contrast is what sets the LiveO2 AC apart from the LiveO2, as the higher your heart rate, the more ‘squirt power’ the oxygen has to penetrate your system when you go back to the live (oxygen rich) mode.
Individual numbers will vary according to age and fitness level, as well as individual physiology differences.