Comfort Patented Ring SensorSoft silicone ring sensor won't make your finger numb and never slips from your finger, which completely frees your finger. Built-in Memory O2Max oxygen reader stores four groups of 10-hour data. When the device is connected to the APP via Bluetooth, the data will be uploaded automatically. All-day MonitoringCheckme O2 Max records your O2 level (blood O2 saturation level), pulse rate, and motion with extremely accuracy. NOTE: It's not a medical device. This device is for Sports and Aviation use only and not intended for medical use. Up To 72Hrs Long-lasting UseNo AAA batteries required, without keeping batteries nearby, continuous using up to 3 days (72 hours) after one charge.