The SBT5K enhances your MP5K with an integral, side-folding, molded polymer end cap. FITS: 2 PIN "K" MODELS SUCH AS HK SP89, HK SP5K, PTR 9KT, CENTURY ARMS AP5-P & AP5-M, MOST SP5K CLONES (9MM ONLY). FEATURES Complete assembly, ready-to-install Molded polymer end cap with QD socket Integral, side-folding mechanism Comes with adjustable nylon strap for custom fit US veteran designed, and proudly made in the USA Due to varying tolerances between roller lock manufacturers, gunsmith installation / fitting may be required.