Generic WY-A1 Universal GPS Speedometer with Over Speed Warning Easy Setup--Plug & Play- Power through Vehicle Cigarette Outlet Jack, No professional installation is required. Compatible with All Cars & Trucks. Use GPS Signal Guided Calculation, No wiring needed to the VSS (vehicle speed signal). Display MPH or KM/h - Simple Push Button Set up. Auto Adjust Brightness thru Sensor for Day & night-time Driving. Vehicle Driving Speed Display, Green Color Speed Display, easy on your eye. Over Speed Warning Setting -- Alarm Mute Function.