Slat nail, #11 X 1-1/2", copper. Recommended for wood and plywood joints where maximum resistance to withdrawal loads is required. Annular ring barbs force wood fibers apart as nail is driven; wood's natural resilience causes the wood fibers to spring back filling the grooves between the rings and creating a locking effect. Nails thus locked in place resist pull-out stresses even when wood swells or shrinks. Not recommended where shear, lateral, or racking loads are significant. Also not recommended for endgrain nailing because wood fibers are not oriented to lock thread. flat head, diamond point