Hoppe's Phosphor Bronze 7.62mm/.308cal AR Rifle Chamber Brush (Pack of 3) Double diameter chamber cleaning brush Phosphor bronze chamber brush features stout bristles for efficient cleaning Stainless steel locking lug brush Standard American 8-32 thread Double diameter chamber cleaning brush for AR style 7.62mm/.308 cal Phosphor bronze brush features stout bristles for efficient cleaning Stainless steel locking lug brush Standard American 8-32 thread; three-pack