‘B-19N upper handguard” milled rail is made of aluminum alloy D16T. Designed to be mounted above the gas tube on following handguards: B-10M, B-10U, B-10L, B-21M, B-21U, B-21L, B-11, B-11U by four screws (in the kit). Forms a Picatinny rail above the gas tube, that does not close the line of iron sight.