B-Line B200SS6 Eaton series strut fittings and accessories, 1.62" Height, 1.62" Length, 1.62" Width, .18lbs, Steel, Square washer, Hole size 3/8 in diameter | Bolt size 5/16 in, Stainless steel type 316

It is Type 316 stainless steel, the grade specified where chlorides are present, so coastal exteriors, wastewater plants, food processing wash-down areas and pool rooms are all normal uses. If your run is indoor dry electrical support, a plain or zinc-plated square washer does the same mechanical job for less.

It is a 1.62 inch square, 1.62 by 1.62 inches, which covers the full width of standard 1-5/8 inch strut and spreads bolt load across the channel flanges instead of dimpling them. Listed height is also 1.62 in, and it weighs .18 lb.

They do different jobs and usually go together. The strut nut goes inside the channel and grips the flange turns; the B200SS6 square washer sits on the outside face under the bolt head, spreading clamping load across both flanges so a beam clamp, pipe strap or bracket does not pull through or distort the strut. Use the washer whenever the mating part is thin sheet or narrower than the channel.

Mechanically yes, but if you specified 316 for corrosion reasons, pair it with 316 bolts and channel nuts. Putting a stainless washer on galvanized hardware in a wet or salt environment leaves the zinc-plated fastener as the part that corrodes first, so the assembly fails at the bolt, not the washer. Keep the whole joint in one material family.

Order by manufacturer part number B200SS6, from Eaton's B-Line series. It is the washer only, sold as a single item with no bolt or channel nut included, so add your 5/16 inch hardware separately.