HHIP Indexable Boring Tool Set with 2" Boring Head, R8 Shank & 4 Boring Bars Boring head features a 1-1/2"-18 threaded back so you can change shanks as needed. A micrometer lead screw provides 0.001" direct reading accuracy and makes adjusting easy. Boring head offset is 5/8". Minimum boring diameter is 0.394". Maximum boring diameter is 5.906". Maximum boring depth is 1.970". The crosshole is 1/2". R8 shank has a drawbar end thread of 7/16"-20. The included indexable boring bars come with TCMT 21.5 C6 carbide inserts for steel and alloy. The set also comes with torx & l-shape hex wrenches and a fitted carrying case. 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.