Metallics WW83BLACK Washer 1/2 USS Flat Wshr BO (100 pcs)

The WW83BLACK is a 1/2 inch USS pattern flat washer, so it goes over 1/2 inch bolts, rod, or threaded fasteners. USS pattern means the outside diameter and hole are the wider of the two common flat washer patterns, which spreads load over a larger bearing area than an SAE washer of the same nominal size.

Use USS, like the Metallics WW83BLACK, when you want a bigger bearing footprint: softer base material, oversized or slotted holes, wood, strut, or sheet metal where the head could pull through. SAE washers are tighter in OD and are the choice when the washer has to sit inside a counterbore, under a small flange, or in a tight bolt pattern where a USS washer would foul the adjacent fastener.

They come 100 to a pack. That is a single bulk count of 1/2 inch USS flat washers, which is how most electrical and MRO stockrooms buy them for strut, rod, and hanger work rather than counting out singles on the truck.

BO stands for black oxide, so the WW83BLACK is a black finished 1/2 inch flat washer rather than bright zinc. It visually matches black oxide rod, strut hardware, and black finished fasteners, which is why it gets specified on exposed overhead runs where shiny zinc would stand out. Black oxide is a conversion finish, not a heavy plating, so it is intended for dry interior use rather than wet or exterior exposure.

Yes. A 1/2 inch USS flat washer is the standard bearing washer under a nut on 1/2-13 all-thread rod, strut nuts, and beam clamps. The wider USS outside diameter is what keeps the nut from pulling through a strut slot or an oversized hole in a channel or bracket. Order the nuts and rod separately; the WW83BLACK pack is washers only, 100 to the box.