Classic Style Bike Speedometer - chrome bezel old school style retro bicycle speedometer with crystal acrylic, looks great on your bike. big in size, easy to read. Easy to Install - simple installation only takes a few minutes. mount the reader on the handlebar, attach the gear to the axle of the front wheel, link them by the cable. no need for batteries and adjustment setting. Auto-reset - there's no reset button. as a mechanical speedo, the odometer will turn to 0 when the mileage reaches 9999.9 to start over. Applicable - perfect for 26/28/29/27.5" road bike, mountain bike, folding bike, and old style exercise bicycles. this speedometer may not be compatible with some electric-assist bicycles. it is not for the quick release wheels that go above 38 mph. Metric Measurement - the speedometer is in kph which is the most widely used measurement, not in mph. a kilometer is 0.62 mile. when the speedometer needle indicates 30kph, the speed is approximately 18.6 miles per hour. Specification: Size: 8x8.5x2cm / 3.14x3.34x0.78inch Material: Plastic Package Includes: 1 Piece Bicycle Speedometer Note: Please allow 1-3mm measuring deviation due to manual measurement. Due to the different monitor and light effect,the actual color of the item might be slightly different from the color showed on the pictures.Thank you!