Extended gas block height. Featuring an easy over-sized push button spring deploy action. Accepts all aftermarket front sight post replacements with Mil-spec dimensions. Sights accepts all aftermarket front sight post replacements with Mil-Spec dimensions. All sights lock in the deployed position. It is not intended for lower height gas block rails. Perfect (M4) co-witness height . Attaches to any 1913 Picatinny rail. Includes stain steel clamp.