Google Fitbit Air

Heart Rate: Optical heart rate monitor that captures data at 2-second intervals. Oxygen & Temp: Red and infrared sensors for SpO2 (blood oxygen) tracking and a temperature sensor for skin temperature variations. Motion: 3-axis accelerometer and gyroscope for activity, sleep stage, and workout tracking. Feedback: Built-in vibration motor for silent alarms, haptic feedback, and Smart Wake features.