Function of magnetic control car instrument, spinning bike instrument: 1. TIME: Press the MODE button to display the time. This value represents the elapsed time of the workout. 2. SPEED: Press the MODE button to display the speed. This value represents the current speed of the movement. 3. DISTANCE: Press the MODE button to display the distance. This value represents the total distance covered during the workout. 4. CALORIE: Press the MODE button to display the calories. This value represents the estimated energy burned during the workout. Compatible with devices that have headphone-style cables. Both speedometer and pulse tracking connections are made through 3.5 mm female jacks on the back of the monitor. Adapters may be required if the connected device also has female jacks (in rare cases). Compatible with most indoor exercise bikes, including stationary bikes with "headphone" style connection tips. Examples include bike models from Sunny, L-Now, Pleny, Faafuu, and other common brands. Fits approximately 95% of home and commercial indoor bikes. Heart rate monitoring feature works with bikes equipped with built-in pulse sensors, typically two metal contact points on the handlebars. Rewiring may be necessary for certain specific models. Requires 2 x AAA batteries (not included). Product dimensions: 108 x 163 mm LCD screen size: 48 x 23 mm Color: White Material: Plastic Package Contents: 1 x Monitor Speedometer with Heart Rate Function Note: Light and screen display differences may cause slight color variations between the product image and the actual item. Measurement error allowance is +/- 1-3 cm.