Apple Watch Series 6-44 mm GPS Aluminium Case 1.78 inches, 10.0 cm2 (~60.0% screen-to-body ratio), Retina LTPO OLED capacitive touchscreen, 16M colors, 448 x 368 pixels (~326 ppi density) . >Built-in rechargeable lithium-ion battery up to 18 hours >Features water resistant depth up to 50 meters >Accelerometer up to 32 g-forces with fall detection >New blood oxygen sensor is made up of four LED clusters and four photodiodes Material of Glass front, ceramic/sapphire crystal back, aluminum frame. Sensor with Accelerometer, gyro, heart rate (2nd gen), barometer, always-on altimeter, compass, SpO2, VO2max Natural language commands and dictation (talking mode). Measure your blood oxygen level with a revolutionary new sensor and app..