Forgefix torx drive csk screws forgefix txfds4550 the forgefix torx drive countersunk screws have a deep torx head for reduced cam out the recessed underhead ribs allow superb self countersinking and a super sharp tip gives immediate bite from the very first turn a unique single threaded spiral shank enables a fast and easy drive into most substrates the countersunk screws are zinc yellow passivated for increased corrosion resistance they have a hardened case and core for exceptional st