Hoppe's 7.62mm/.308cal AR Rifle Brush Multi-Pack (Chamber Brush, Chamber Mop, Bore Brush) 100% cotton chamber mop Double diameter phosphor bronze and stainless steel chamber cleaning brush Phosphor bronze bore brush Standard American 8-32 thread AR Style 7.62mm (.308 cal.) Multi-Pack Chamber Brush, Bore Brush and Chamber Mop 100% cotton chamber mop Double diameter phosphor bronze and stainless steel chamber cleaning brush Phosphor bronze bore brush Standard American 8-32 thread