Samson fixed sights are the most robust fixed combat sights on the market. Available with the sightlink fiber optic front sight post. Accepts all aftermarket front sight post replacements with Mil-spec dimensions. It is not intended for lower height gas block rails. The durable construction and solid mounting system guarantees you to stay on zero.Features :Fixed front sightAttaches to any 1913 picatinny railPerfect (M4) co-witness heightStainless steel clamp