Boxes, Square, Appleton, Type: 4" with knockouts, 1-1//2" deep, welded, 1-3/8" offset vertical bracket, Volume: 21 Cubic Inch, Sides Knockout: 6@1/2", 3@ Eccentric KO, bottom Knockout: 2@1/2", 2 Eccentric KO, UL Standard: 514A, UL Listed: E2527, NEMA: OS