TangoDown, Vickers Tactical Slide Racker For Glk, Standard Size, Black The GSR Slide Racker is a top quality drop-in part, requiring no other modifications to the firearm. Injection molded of glass-reinforced nylon with stainless steel reinforcement just like the OEM part, it replaces the striker retention plate in minutes. Once in place, the GSR offers easy, effortless and positive slide cycling under any condition.