"The GenReady Load Center replaces the main circuit panel and has the ability to incorporate an automatic transfer switch EZ Transfer Operator, Item# 165890 so all power switching is handled within one unit. It then becomes a hybrid panel capable of separating out only the electrical circuits the homeowner chooses to back up during a power outage. U.S.A. Amps 125, Dimensions L x W x H in. 42 x 15 x 4, Application Load center. 40 circuit capacity with the use of tandem breakers Dimensions the same as a standard 42 circuit main load center 42in.L x 15in.W x 4in.H Uses standard Siemens load components Works with Generac generators rated up to 125 Amps/30kW"