Designed to provide trouble-free changeover of power between shore power and generator. This is used for a 30 Amp AC services. Can be installed onto the back of WFCO 8900 Series Power Centers. It is engineered for safe, reliable performance, and the unit’s DC coil prevents AC "chatter" noise and drop-out in low-voltage conditions. Accidental coupling of power from or to shore line and generator is prevented by a "break before make" configuration.