Specification Bluetooth: Bluetooth 5.1 Matching Systems:Android 5.1 or iOS 10.0 or later Screen: OLED，0.49 inch，72*40 Battery capacity:40mAh , Charge case battery capacity: 120mAh Material:stainless steel Button:1 button Charging port: Pogo Pin Theoretical working hours: The ring battery and charging case both provide 15 days of use for the ring under normal conditions. Sensors:Vibration Motor Size: 20mm Weight: 11.7 Color: Graphite