CLASSIC STYLE BIKE SPEEDOMETER: 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: Speed In RPM Odometer 24-27.5 Inch Wheels. Perfect For 26-27"" 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.