2" 1-1/2~18 Boring Head ~ Tool capacity is up to 1/2". ~ Maximum offset is 5/8". ~ Graduation is . 0005". ~ Bar holder moves freely and smoothly. ~ Design assures superior rigidity for chatter-free boring and precise hole size accuracy. ~ Hardened and ground adjusting screw is designed too last long and provide trouble free use. ~ ~ A micrometer lead screw provides 0. 001" direct reading accuracy and makes adjusting easy. ~ 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.