B-Line 4D21SH-120GLV Eaton series 4Dimension strut channel

Pre-galvanized (GLV) steel is the standard finish for indoor and protected applications, such as mechanical rooms, above ceilings, and interior electrical rooms. The zinc is applied to the coil before forming, so the cut ends and punched slots are bare steel. For direct weather exposure, a wash-down area, or a corrosive environment, specify a hot-dip galvanized or stainless strut instead.

The 4D21SH is formed from 18 gauge steel, which is the light-duty end of the strut range and is aimed at supporting conduit, small cable tray, low-voltage runs, and light fixture hanging. For heavier mechanical loads, long unsupported spans, or trapeze hangers carrying pipe, step up to a heavier gauge and a deeper channel profile.

The open face of the 4D21 measures 2.12 inches across the outside, the common 1-5/8 nominal strut dimension, so ordinary 1-5/8 spring nuts, channel nuts, and fittings engage the inturned lips. Watch the depth: at 1.06 inches tall, this is a shallow channel, so deep-throat fittings and some conduit clamps sized for a 1-5/8 by 1-5/8 deep channel will bottom out. Match fittings to a half-height profile.

SH is the slotted hole pattern on the back of the channel, versus a plain solid-back stick. It gives you bolt-through points along the run without field drilling, which matters when you are anchoring the channel flat to concrete, deck, or a wall rather than hanging it from rod. The channel type itself is 4D21.

Order B-Line 4D21SH-120GLV. Read it as a 4D21 channel type, SH slotted hole pattern, 120 inch length, GLV pre-galvanized finish. If a drawing calls out a solid back, a different length, or a hot-dip finish, the suffix changes and it is a different part.

A full 120 inch stick weighs 10.32 lb, about a pound per foot. That is light enough for a single installer to carry and set a run overhead without a second pair of hands, and it is the number to use when you are totaling weight for a bulk delivery or a pallet of sticks.

Yes. It is formed steel at 18 gauge, so a bandsaw, chop saw with a metal blade, or portable band saw cuts it cleanly from the 120 inch stick. Because the finish is pre-galvanized, the fresh cut leaves bare steel at the end, so touch cut ends with a cold galvanizing compound if the run is anywhere damp, and file the burr before sliding a nut past it.