Square Washers called construction square plate washers can be used instead of round washer for applications such as timber building and concrete floors; they are used with all fasteners for larger load distribution and bolting through a wall or timber. While disc washers operate solely as load distributors, square flat washers serve a second role. Their thick metal forms have that standard bolt opening in the center, plus a wide surface area, a feature that spreads torque and head load, but they also perform as shims. That means the bolt crown can be lifted away from the anchored part. It also means that a multi surface project won't deform or bend when the fastener is tightened. Available in hot dip galvanized finish, which provides a corrosion resistant zinc coating.