The most trusted way to transfer power between shoreline and RV generator switches, Parallax's ATS 503 is designed to transfer power with ease regardless of the line voltage conditions. The new ATS 503 eliminates the hassle of handling plugs or electrical cords to transfer power. Designed for 120/240VAC 50 amp service, features include large robust relay coils to maintain position during transfer switch operation while the coach is in motion, heavy duty galvanized steel chassis, shore/utility power is the default power source while the generator/alternate serves as the ??es command(TM) power source, reduced arcing and system voltage dropouts prevent damage to your equipment, heavy duty, high performance contacts, excellent relay and PCB protection against damage, LED diagnostic self-checking indicators, control board provides capability for future expansion and easy to wire/install. Dimensions: 4(TM) H x 12" W x 10(TM) D. Weight: 10 lbs.