Bluetooth 4.0 low energy technology to synchronize phone APP application, real-time data recording detection status accurate data, provided the highest average heart rate, exercise time and other data accurately monitor heart rate and calorie consumption, while continuing to observe changes in heart rate, helps to understand their own physical condition, adjust training methods to enhance cardiorespiratory endurance Specification: Brand new Color: Black The transmitter section Material: ABS Heart rate belt Material: rubber + plastic Bluetooth 4.0 low power transmission, cooperate with APP to use, data wireless transmission Chest strap length adjustment range: 70-120CM (adjustable) Power: CR2032(Include),can be used about 700 hours Waterproof and sweat, easy to clean Size: 28*35*10MM Weight: 45g Device Requirements: Android 4.4 and later, IOS system and a mobile phone with Bluetooth Package included: 1 * Heart rate chest band 1 * Built-in CR2032 button battery 1 * Instruction manual Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.