The AAIS Rail set, Part number BT20 consists of three pieces of 1913 rail that can be attached to the AAIS BT19 on the bottom and both sides allowing for a multitude of options including mounting of the BT10 and BT10-LW17 to the AAIS. These rails are made from 6061T6 Aluminum with a type II hard coat anodize and come complete with fasteners they are proudly made in the USA.