Mayhew’sPneumatic Flange Nut Drivers are unique counter-bored drivers specifically designed to drive flange-head fasteners, bolts, pins, or rods. The drivers fit over the hex head of a Flange Nut or Bolt, using the flange to drive the nut or bolt in or out without damaging the hex head and can also be used to drive any bolt, pin or rod that fits the counter-bore without sliding off.