WTEK HS-2+ Ant+ Wireless Heart Rate Sensor Design and technology combined together have created a unique product. The HS- 2+ is a sensor that has a thickness of only 8mm and a diameter of 4 cm. You can put it in your pocket and take it with you! Thanks to the winged hook system you can clip the sensor to any wrist or sweatband. The fins are ergonomically designed and functional, which means its simple and straightforward to wear the sensor. Thanks to the innovative pulsed light technology WTEK eliminates the need for uncomfortable chest straps! The WTEK pulsed light technology is extremely innovative and is the only application of such in the world. Resulting from five years of research and development, it is ultra-low power, reliable and appreciated by countless sports and fitness professionals. Activate the switch with a simple push of a button. The WTEK optical sensor is activated by pressing the button, and at the end of your workout it is deactivated by pressing the button again, the green LED turns off thus preserving battery life