GPS speedometer: collecting real time speed from GPS satellites. 4.2 inch big screen size and green font display make more easily and comfortable to read. Compass display, compass will not be affected by geomagnetism, driving direction is the compass direction. Driving time and distance calculation and display. Plug & play: (5V) through vehicle cigarette outlet jack, no installation is required. Display MPH or KM/h - Simple push button set up. Auto adjust brightness through sensor for day & night-time driving. Over-speed and Fatigue driving warning. Universal: compatible with all , trucks, bikes, & motorcycles. (note:when using with the bicycle, pls use the usb cable connecting with a powerbank.) Safety: 1. The case is made of ABS+PC, which is high temperature resistant anti-fire material. 2. No built-in battery, no explosion/no burning hazard under high temperature. Specification: GPS positioning time: 1 to 5 minutes in the open (the bad weather will affect the positioning time), there is no GPS signal indoors, inside tunnel or under garage. Input Voltage: DC 5V Working temperature: -30 to 80 degree Working humidity: 20%~85% Colour:black Material:ABS+PC Size:122 x 62 x 38mm Package Contents: 1 x HUD Display C3010 1 x Holder 1 x USB cable 1 x English manual Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.