iManson Bike Computer Wireless Waterproof Cycling Computer With Heart Rate Monitor,Speedometer,Odometer and Calorie Counter CORE FUNCTIONS 3 IN 1: Heart Rate Monitor, Speedometers, Cadence Sensor. MULTI FUNCTION: Speed comparing, Average, Maximum, Relative, Riding time, Riding distance, Measurements, Auto ON/Off, Scanning, EL Backlights,Comfortable and User friendly. AUTO SLEEP/WAKE: Auto wake 10 seconds ,auto sleep 5 minutes during inactive use;Total distance for bike1+bike2. WATERPROOF DEVICE: Riding in a rainy day is ok, but not soak in water or put in rainstorm for a long time. ANTI SIGNAL INTERFERENCE: It won't interfere other wireless & electronics devices, wireless ranged less than 30 cm, accurate data result.