IRWIN Tools Auger Bit with Weld Tec, 9/16-inch by 7 1/2-inch, 7/16-inch Shank (1779138), Auger Bits with Weld Tec, Weld Tec Ship Auger bits are MADE STRONGER and LAST LONGER because a harder cutting edge is welded to the base material, 2X Nail Cutting Life compared to standard IRWIN ship augers