Square Washers

Square Washers.Square washers fit into slots and channels and have flat sides to keep them from rotating. They are wider and thicker than most round washers, making them good for distributing heavy loads.
316 stainless steel washers have excellent resistance to chemicals and saltwater. They may be mildly magnetic.
18-8 stainless steel washers have good chemical resistance and may be mildly magnetic.
Black-oxide steel washers are mildly corrosion resistant in dry environments.
Zinc-plated steel washers are corrosion resistant in wet environments.
Galvanized steel washers are 10 times as corrosion resistant as zinc-plated steel washers.    

Square Washers for Blind Rivets.Also known as backup washers, these square washers are for use with blind rivets for extra support when fastening into soft material. They fit into slots and channels and have flat sides to keep them from rotating. They are wider and thicker than most round washers, making them good for distributing heavy loads. They are zinc-plated steel for corrosion resistance in wet environments.