AutoFuse™ automatically disconnects manufacturer recommended fuse during dingy towing, helping to avoid a dead battery. Easy 20 minute one time installation eliminates the need to look under your cars hood and pull the proper fuse, forever. Green warning light confirms proper operation. Device also provides trickle charge to help maintain your towed vehicle batteries. Rugged aluminum case and weather resistant fuse holder ensure reliability. Don't get stuck with a dead battery when you arrive at your destination!