With PPG technology, this product can detect users’ heart rate information by itself. Unlike traditional heart rate chest belt, our TXGD provides more convenience to wear and allow users to feel more comfortable while exercising. By using BLE4.0 and ANT+ transmission, it can pair with most cycle computers and smartphones in the market. TX-GD is an optical heart rate monitor, with a fabric band that combines comfort and simplicity. It fits comfortably around your wrist or arm and tracks heart rate with 2 high-quality optical heart rate sensors. If you are not a fan of chest belt, this device is a great alternative for you. This heart rate sensor streams real-time heart rate to GPS series: GPS-100, GPS200, MR-Fit, and MR-Connect and many others compatibles with BLE 4.0 fitness APPs. LED Indicator: Blue, Green, Red, and White Charging time: 2 hours Sensor Dimension: 30,2 mm x 37,9 mm Wrist Band Dimensions: 265mm x 25mm Transmission distance: 2.5 m