FAB Defense M4 Collapsible Buttstock System for H&K G3 Black M4G3-FK. Specifications for FAB Defense M4 Collapsible Buttstock System: Manufacturer: FAB Defense Gun Type: Rifle Fabric/Material: Polymer Features of FAB Defense M4 Collapsible Buttstock System The M4-G3 FK Collapsible Buttstock for the Heckler and Koch G3 is an M4 style collapsible buttstock with 5 optional length positions for enhanced performance and versatility. Advantages: Provides optimal eye to target alignment Made from 6061 T6 Billet aluminum and fiberglass reinforced polymer composite Replaces the original stock and securely attaches to the G3 back plate Integrated Quick Detach sling swivel connectors on both sides Enhances natural fighting stance and hold on your G3 Rubber butt-pad reduces slippage Intergrated storage compartment for 2x CR123 / AA batteries Package Contents: FAB Defense M4 Collapsible Buttstock System What firearm models does the manufacturer say FAB Defense M4 Collapsible Buttstock System is compatible with? The manufacturer says that FAB Defense M4 Collapsible Buttstock System is compatible with CZ Sa vz. 58 Heckler & Koch G3FAB Defense M4G3-FK: M4 Collapsible Buttstock System for H&K G3 Black