Rail section is made of Lightweight Impact Resistant Polymer; Mounting hardware is made of Corrosion Resistant Stainless Steel; Made to the Mil-Standard 1913 Picatinny Arsenal Specifications; Lengths: 4-inch (7 slot); Features a Snag resistant design, while retaining Mil-Standards specs; Self-contained assembly, eliminates the possible loss of mounting hardware; Fits ALL KeyMod interface mounting surfaces; Black Finish