ESF (End plate, Sling Adapter, Forward Controls Design) is a drop in end plate replacement for the AR platform (both 223 and 308 spec).  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 on the RE (#1 position being fully closed) if a rear facing QD swivel is present.

ESF is available in 7075 aluminum, anodized ESF-L (0.39oz), and 4140 steel, DLC coated ESF-H (1.10oz) versions.  Both ESF versions have rotation limited side facing sockets.  The rear facing socket has no limiters, as the receiver extension effectively limits the swivel’s rotation.  From late 2018, non-rotation limited side QD socket option has been deleted, all ESF-L and ESF-H have rotation limited side facing QD sockets)