Dale Fastener Supply stocks a variety of Square Strut Washers, Square Channel Washers, and Square Dock Washers that are made from zinc-plated steel, hot-dipped galvanized steel, and 316 stainless steel and are available in various sizes. Square washers are often used in construction where building codes specify the channel washer as a structural component of framing and other subsystems, or in channels or struts.