Use this Stock Folding Mechanism / Folding Stock Hinge with Manticore , ACE, Tromix , HDPS skeleton stocks, as well as StormWerkz Universal Carbine adapter which uses Ar-15 carbine stocks. -This hinge locks solid in both positions -Tapped for sling stud -Mounting bolts(10-32 Socket Cap Screws) included -Mounting holes are .625 center to center