The 4 Amp Waterproof Charger/Maintainer is sealed to protect against moisture, corrosion, dust and oil. The fully automatic operation charges and maintains battery charge levels. The smart charge microprocessor automatically selects charge rate and adjusts from rapid charge to maintainer to maintain battery life. Compatible with any AGM, GEL, or WET 12 Volt battery. Includes battery clamps and battery terminal rings. Built in circuit protection and reverse polarity, with AC low-voltage compensation. New.