The Battery Tender Solar Charger 021-1178 is a solar-powered battery charger designed to keep 12-volt batteries charged and maintained. It features a built-in charge controller to prevent overcharging and a 3-step charging program to ensure maximum battery life. The charger is weatherproof and can be mounted on a variety of surfaces, making it suitable for use in outdoor environments. It is compatible with all types of lead-acid batteries, including AGM, gel, and flooded. The charger also includes a 10-year warranty for added peace of mind.