SLB Works 12/24V 85mm 4000RPM Waterproof Variable Backlight Digital GPS Gauge Speedometer Odometer Marine Boat Specification: product name: gps speedometermaterial: 316l stainless steel bezel, plastic housingcolor: black face, silver frameoperating voltage: 9~32vdcoperating current: Ãâ€°Â¤ 100ma(24v);operating temperature: -30~+75Ã£Ãâ‚¬Å¾Ã¦â€storage temperature: -40~+85Ã£Ãâ‚¬Å¾Ã¦â€diameter: 85mmÃ speed ratio adjustment: 1)press the set button (less than 1 second) to change the backlight color: backlight changed in sequence: red (default) Ãâ€ green Ãâ€ blue Ãâ€ white Ãâ€ yellow Ãâ€ yellow green Ãâ€ orange Ãâ€ purple Ãâ€ (automatic).Automatic: as the gauges was set with the automatic, the backlight will be off for 2 seconds then lighten up, and will switchthe backlight color as above sequentially. 2)press the black rubber mode button on the instrument for 3 seconds, then it will enter into the speed ratio setup mode, if thebutton is released for 3 seconds, it will exit the speed ratio setup mode, and automatically retain the setting data. 3)as the tachometer is in setting mode, press the button to select the speed ratio required, dey as down below form. Forinstance, the pointer point at 1000rpm is for 2 cylinder engine. Ã‚ note: 1. Please allow 1-2mm error due to manual measurement. Pls make sure you do not mind before you bid. 2. The color may have different as the difference display, pls understand. Ã‚ package included: 1 x gps speedometer1 x wiring harness1 x user manual