Special, small stainless brushes for removing those stubborn deposits on the very bottom of dive tanks. Each brush screws onto a 3 - foot aluminum rod which fits into any 3/8 electric drill. Each unit comes with the brush, extender rod, and a plastic guide sleeve to augment insertion through tank necks. Fine wire for light rust sports in steel tanks or Bayerite deposits in aluminum models. Will not seriously damage the interior coatings of aluminum tanks. Order #43041 for replacement brush only.