120 VAC 50-Amp Automatic Transfer Switch Heavy duty relays prevent contact damage during high current transfer operation. Quick change circuit board easily replaced in the event of failure. No need to disconnect and reinstall entire unit. Time delay circuit board ensures generator voltage is at proper level before transfer occurs. Built-in strain reliefs allow the installer to simply push the branch circuit wires inside the unit for connection. Eliminates the need to purchase and install separate strain reliefs for each circuit. Screw-type wiring terminals ensure ease of wiring and prevent wiring errors. Protective cover easily snaps on or off. Handy wiring schematic mounted inside the cover.