The Washer Anti-Locking Captivation or WALC™ solution prevents captivated washers from sliding over the thread like regular SEMS. The unique design of WALC™ provides the perfect answer for SEMS in automated assemblies. Washer Anti-Locking Captivation makes it impossible for the washer to lock. By serrating the partial thread beneath the screw head, WALC™ becomes integral to the screw thread and extends for 1 pitch minimum from the washer bearing surface.