This aftermarket HK 91 Carbine Length M-lok Handguard fits most 5.56 HK rifles, and carbine length 7.62 clones. This sleek streamlined design is an ultra low profile handguard with generous mounting space to accept all M-Lok accessories. Superior ergonomics and simple, drop-in installation makes this the best HK pattern rail on the market. Lightweight and durable. Length. 9.6 inches. Black anodized 6061 T6 aluminum.