Used Sig 556, 1st gen configuration, so it takes standard AR extension tubes/ stocks. Comes with the original Sig 30rd magazine and coupler. Less than 1000rds through the pipe. Has the swiss bayonet/tripod lug installed, swiss bayonet included. Magpul trigger guard. The stock birdcage hider has been upgraded to a YHM phantom fh. Asking $1400.