Function of magnetic control car instrument, spinning bike instrument: 1. TIME: Press the MODE button to display the time. This value represents the time from the start to the end of the movement. 2. SPEED: Press the MODE key to display the speed. This value represents the speed of the current movement. 3. DISTANCE: Press the MODE key to display the distance. This value represents the distance from the start to the end of the movement. 4. CALORIE: Press the MODE button to display the calories. This value represents the energy burned from the start to the end. Works for HeadPhone-Look Cables. Both speedometer & pulse tracking connection are through 3.5 mm female jacks on the back of the monitor - adapters (NOT INCLUDED) might be needed if the device also happen to have FEMALE jacks (rare cases). Compatible with Most Indoor Exercise Bikes - for Stationary Bikes with "head phone" look connection tips. E.g. many bike models by Sunny, L-Now, Pleny, Faafuu - 95% of as well as domestic bikes. Heart Rate Monitoring Feature that works with bikes with pulse sensors (usually 2 x metal pieces on handlebars). Re-wiring MIGHT be required for some particular models. 2 x AAA Batteries Not Included - Required. Batteries are NOT included. Product size: 108x163mm LCD size: 48x23mm Colour: white Material: plastic Package Contents: 1 * Monitor Speedometer W/ Heart Rate. Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the photo a little different from the real thing. The measurement allowed error is +/- 1-3cm.