2.4W (watt) solar battery maintainer. Connect solar panel to battery when not in use. Automatically maintains battery without electricity to extend battery life - reliable and environmentally-friendly. Rugged design works in all weather conditions. Water resistant. Thin film technology allows panel to absorb a larger spectrum of light so that it works under cloudy conditions. Plugs into 12V (volt) accessory outlet or directly to battery. Ideal for boats, cars, motorcycles, snowmobiles, trucks, RVs and more. Complete with battery clamps and 12V plug.