Battery Tender Twin 800 12V Dual Battery Charger Built-in "Supersmart" technology directed by the unit's IC chip not only fully charges your vehicle's battery when not in use, but safely maintains it at the proper storage voltage via float charge Sparkproof, as well as short circuit and reverse polarity protected Dual DC output and long cable capacity allowing for two batteries to be charged at once from a distance Easy to see, read and understand battery charge status indicator light display Classic V-Twin motorcycle outer housing mimics the sound of a motorcycle engine starting when you connect the charger to a battery