Grizzly G9324 Boring Combo Set, 3-Inch Just like the individual boring heads these combination sets provide maximum rigidity even when the boring bar holder is used in an offset position h Hardened and ground adjusting screws along with a wide base design guarantee a long life and trouble-free use Model g9322 includes: 2-Inch boring head r-8 shank with 7/8-Inch-20 tpi and 9-piece 1/2-Inch boring bar set