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 USADue to varying tolerances between roller lock manufacturers gunsmith installation / fitting may be required.