3MT Boring Tool Set ~ Includes a 2" Head, an 3MT Shank, and a 1/2" 9 Piece Boring Bar Set ~ The boring head bar holder moves freely and smoothly. ~ The boring head design assures superior rigidity for chatter-free boring and precise hole size accuracy. ~ The boring head has a hardened and ground adjusting screw designed for long lasting and trouble free use. ~ The tool capacity is up to 1/2". ~ The shank to the head is 7/8"-20. ~ The 3MT shank has a 3/8"-16 thread. ~ 1 DIV = 0. 001 which means when turning the dial by 1 division/graduation, the boring head's travel is 0. 001" in radius movement and 0. 002" in diameter movement.