B-Line B201YZN Eaton series strut fittings and accessories, 1.62" Height, 1.62" Length, 1.62" Width, .18lbs, Steel, Square washer, Hole size 7/16 in diameter | Bolt size 3/8 in, Yellow zinc chromate

It measures 1.62 x 1.62 x 1.62 inches. The 1.62 inch face is wider than the open slot of standard 1-5/8 inch strut, so the washer bears on the inturned lips of the channel rather than dropping through, which is the whole point of a square washer over a round flat washer on strut.

Yes. The square washer is a bearing plate only, not a fastening component. A complete 3/8 inch strut connection is the channel nut with its spring, the 3/8 inch bolt or all-thread rod, and this washer under the bolt head or nut to spread the load across the channel lips. Order the nut and the bolt separately, in a matching 3/8 inch size.

It will. The 7/16 inch hole clears 3/8-16 all-thread, so you can run the rod through the washer and lock it with a nut above and below. This is the standard way to land a rod on strut when the rod passes through the channel face instead of terminating in a nut. Steel construction throughout.

Yellow zinc chromate over steel is a plated indoor and sheltered-location finish. It handles the humidity of a mechanical room, a parking garage soffit, or a covered loading dock. For direct weather exposure, roof-mounted runs, or a coastal site, step up to hot dip galvanized or stainless strut hardware instead, and keep the finish consistent through the whole assembly so you're not putting plated steel against stainless.

B201YZN is the manufacturer part number, from Eaton's B-Line series of strut fittings and accessories. The YZN suffix is the yellow zinc chromate finish, so if a submittal calls for the plain electrogalvanized or galvanized version of the same 3/8 inch square washer, you want a different suffix on that base number.