Unique thread design forms mating threads in the crossmembers 50% greater thread engagement for increased resistance to strip-out and pull-out Requires 40% less drive torque Greater tolerance to hole size variation Patented TORX drive head permits non-slip installation Phosphate- and oil-coated black finish The best screw available for truck trailer floor board installation TORX Drive Bit T40 fits 5/16" dia. screws. Recommended drill bit sizes: 9/32 for steel; H for aluminum.