This rifle is a hard to find SIG 556 Commando, a limited Edition, along with a SIG 551 complete lower receiver assembly that was finished to match the 556 upper. In addition the rifle is equipped with a SIG Diopter Rear Sight The 556 comes with the sig magazine and the 551 lower has 3 Swiss 551 magazines. This rifle is a safe queen and has only been test fired once.