The Forward Controls Design ESF is a end plate replacement for the AR platform. Featuring three quick detach sling swivel sockets (two side, and one rear facing), when used in conjunction with a castle nut, ESF will allow retractable carbine stocks to fully collapse. SOPMOD and B5 Systems Bravo stocks will fully collapse with a rear facing QD swivel installed, other carbine stocks must be closed on the #2 position if a rear facing QD swivel is present. ESF-H has rotation limited side facing sockets. The rear facing socket has no limiters, as the receiver extension effectively limits the swivel's rotation.