It's the tactical XM15-E25 16" A2 upper, on a Delaware Machinery lower, with the big DM on the mag well, has a 6-position collapsible stock. Has a low profile gas block added where the original gas block/front sight was, and the front sight has been moved forward to accomadate the handguard for a 20" AR rifle. Clean rifle, low round count. $750 OBO