According to ASTM D5933, the specification covering shear plate timber connectors, they are, “Round, cast, or stamped disk-like load-transfer devices having a flat base and a perimeter bearing rim protruding in one direction normal to the base, with a hole passing though the center of the disk to accommodate an attachment bolt or lag screw.” Shear plates increase the strength of the joints in timber construction by providing a large area for the surrounding timber to bear against. This eliminates the small bearing area provided by a bolt, and enables the stresses to be distributed over practically the entire cross section of the timbers involved.