FAB Defense M4 Conversion Kit is a precision stock upgrade for Ruger 10/22 rifles (standard, bull-barreled, or silenced), converting them to an M4-style collapsible, left side-folding configuration with adjustable length of pull. Constructed from durable, lightweight fiberglass-reinforced synthetic polymer in matte black finish, height 5.78, width 3.93, weighing 37.50 oz. Features an ultra-rugged, slightly angled design to counter recoil and improve on-target time and muzzle control. Includes four integrated QD rear sling swivel connectors. Compatible with all 1913 Mil-Std Picatinny-based optics and accessories. No gunsmithing required. Safety note Follow all manufacturer installation instructions. Verify proper function and secure mounting before use. Comply with local firearm laws and regulations.