So here’s a little background first and remember this only applies to the 60 & 100 amp products. Our 20 & 30 amp product still have back boxes. Our competitors sell either male or female flanged devices for panel mounting and when you want to wall or surface mount them you buy a back box to provide mounting for the flanged device. We switched to an integrated device several years ago to allow for more wiring room and to lessen the chance of leakage. Our devices have no joint between the back box and the flanged device therefore no chance of that connection leaking. The design also allows for a larger wiring space.
Male Flange “B” + back box = “I” Surface Mount Inlet
Female Flange “R” + back box = “W” Surface Mount Outlet