Nature Power 40019 2-Watt Solar Powered 12-Volt Battery Maintainer Keeps your vehicle batteries charged; works with all 12-volt rechargeable batteries including those in vehicles, boats, farm equipment High quality amorphous solar material will work in all light conditions even on overcast days Weatherproof for outdoor use Battery clamp, 12-volt car plug and flat or tilted mounting hardware included Provides up to 2-watt or 0.13 Amp per hour of sunlight