The strike ar picatinny stock adapter mechanism threads into a standard ar rear 1 3/16"-16 hss right hand thread and has an anti-loosening detent that is very positive and tactile while keeping the rear detent spring captured for the rear takedown pin.The 1913 picatinny section of this adapter includes a 4-slot rail section.As an added feature there is a 360 free swivel qd socket that the user can orientate to either left or right side to best configure the preferred setup.Compatible with majority of folding stocks or stabilizers on the market.When you want to use an upper receiver where everything is self-contained quickly convert your ar lower receiver to mount a picatinny stock or stabilizer with the strike ar picatinny stock adapter.Type: Stock AdapterMaterial: 6061-T6 AluminumFinish: Anodized