B-Line Eaton series strut channel, .81" channel height, 120" channel length, 1.62" channel width, Steel, 12 Gauge, S hole pattern, B52 channel type, H

The B52 is the shallow one. It measures .81 in high by 1.62 in wide, so it is the half-height profile with the standard 1-5/8 inch strut face width. Nuts, straps and fittings sized to a 1-5/8 inch strut opening will seat on it, but it has roughly half the depth of a 1-5/8 by 1-5/8 channel, so it carries less load. Use it where the run is tight to a ceiling or wall and the loads are light.

Yes. The finish is hot-dipped galvanized steel, which is the finish specified for exterior, damp, and unheated spaces such as rooftops, parking structures and wash-down areas. Pre-galvanized (electro-galvanized) strut is the indoor-dry equivalent and should not be swapped in outdoors. Cut ends should be touched up with a zinc-rich coating since cutting exposes bare steel.

The channel face is 1.62 in wide, the standard 1-5/8 inch strut opening, so spring nuts, channel nuts, pipe clamps and straps built for 1-5/8 inch strut engage the lipped opening normally. Watch the fastener length: with only .81 in of interior depth, a long bolt can bottom out against the channel back before it clamps. Order bolts sized for half-height channel.

S means slotted back. The B52S carries B-Line's S hole pattern along the channel back, so you can bolt the strut to structure at intervals without field drilling. If you want an unpunched back for a continuous run, that is a different suffix, not the S.

The part number is B52S-120HDG: B52 profile, S slotted pattern, 120 inch length, HDG for hot-dipped galvanized. It ships as bare channel. Nuts, bolts, clamps, end caps, and brackets are separate line items, so build those into the order before the crew is on the roof.