12V car battery meter, monitoring the charge state of 12V battery bank Feature 1. Display your vehicle' s voltage output in style, whether for performance audio or just for show 2. One premium 12V red digital voltmeter display gauge 3. Automatically turns on when car is powered up and then off when car is shut off, except on vehicles with a constant powered 12V jack 4. Plugs directly into any 12 volt cigarette adapter for an effortless install 5. Gives your vehicle a great custom unique look 6. High grade plastic housing ensures long life and durability 7. Auto zero setting Specification: Power supply: DC12V( car) / DC24V( Truck) Digit: 3 digits Range: 8-30V Operating temperature: -5~ 60 degrees Net weight: 32g You can know the state of auto storage battery any time so that You can control your auto more easy and more safe. You can only install our voltmeter in the cigarette lighter when you want to voltage of auto battery Thanks for reviewing!