With flat sides, these washers fit into slots and channels and won't rotate out of position. They are also wider and thicker than most round washers, so they distribute heavier loads across a larger surface area. Square washers are commonly used to anchor heavy machinery, fasten framing to floors, and hang pipe and conduit from strut channel.

Narrower than clipped and square washers, these fit in the thinnest channels and slots. When positioned against a flat edge, they won't rotate out of position, so your assembly stays stable. Rectangular washers have a large surface area to withstand heavy loads and distribute pressure evenly under nuts and screws. They are commonly used to anchor heavy machinery, fasten framing to floors, and hang pipe and conduit from strut channel.