The LENYES LW-209 wireless smart watch features a comfortable and durable silicone watch band. Stay connected and track your fitness with this sleek and modern accessory. Specifications Appearance material: zinc alloy + IML process case, electroplated anti- fingerprint strengthened mineral glass mirror. Charging time: 4 hours. Duration of use: 3---10 days. Waterproof grade: IP67 waterproof. Compatible system: IOS, Apple IOS 10.0 or above / Android system, support Android 4.4 and above. Flash memory: 128MB. 130 sports modes. Screen size: 1.46 inch IPS full viewing angle color screen Resolution: HD 360*360. Bluetooth: Dual Bluetooth 5.0. Heart rate: Zhan Heng BD1662_I2C (true heart rate true blood oxygen).