The BLACK DECKER BM3B high frequency battery charger and maintainer is used to keep batteries in stored vehicles and battery applications at optimal capacity during the off season. Charges 6 volt and 12 volt AGM, GEL and WET batteries in RVs, specialty vehicles, antique and classic cars, marine deep cycle batteries, motorcycles, lawn mowers, ATVs, snowmobiles, and personal watercrafts. Slide the voltage selector switch to either 6V or 12V depending upon the battery you are charging. Connect the battery charger and maintainer with the included battery clips or battery ring terminals. Charging automatically stops when battery is fully charged or topped off and switches to float mode monitoring to maintain charge. Built-in circuit protection guards against overcharging, reverse polarity, or short circuit and is ETL certified for performance and safety. The BLACK DECKER BM3B battery charger and maintainer has a built-in mounting bracket for convenient placement and includes a limited 1 year manufacturer warranty.