4", new construction recessed housing, air tight, for use with insulated ceilings, pre-installed bar hangars fit up to 24" spacing, t-bar clips for drop ceilings, 5-1/2"h fits 2" x 6" joist construction, adjustable porcelain socket, integral thermal protector, 7 junction box conduit knockouts are uniform 1/2" size with true pryout slots, 4 pryouts with integral strain relief for non-metallic sheathed cable, 3 push in wire connectors for easier installation, 4-1/2" opening, 120v, compatible with halo 4" trims, ul/cul listed for damp location.