AR-15 END PLATE W/ 3-QD SLING SWIVEL SOCKETS STEEL As is FCD's practice, ESF's shape is dictated by its functions. In order to accommodate the rear facing socket, and fill one of the design requirements that ESF must be able to use stakable castle nuts and allow the carbine stock to fully collapse, ESF has a slight increase in width on the sides, and small openings on the top of the sockets housing. These design cues do not affect ESF's structural integrity, and mostly go unnoticed by users, they merely reflect a paradox, that it can be quite complicated to create a simplified design. A seemingly simple product can often be more than meets the eye. End plate Mfg: Forward Controls Design