B5 Systems Sierra K Stock is a black compact buttstock optimized for PDW and compact weapon systems, mounting via the Sierra K receiver extension kit. Features a slim ergonomic cheek weld, snag-free low-profile adjustment latch, internal tensioners, ambidextrous fixed sling mounts and limited rotation QD mounts, and an anti-slip buttpad. Made of Mil-Spec materials and finishes with color-matched steel hardware. Length 5.63, height 3.80, width 1.50. Weighs 6.60 oz. Safety note Follow all manufacturer installation instructions. Verify proper function and secure mounting before use. Comply with local firearm laws and regulations.