One-Button Operation: Put your finger into the hole, press the button (keep still) and wait for 8 seconds. The pulse oximeter can monitor blood oxygen saturation You Will Get: Pulse oximeter* 1, AAA batteries* 2, belt loop* 1, neck cord* 1, manual* 1.
https://www.amazon.com/Oximeter-Fingertip-Saturation-Metene-Batteries/dp/B0828WFD5J