MT1 Carbide Tipped, Half-Notched Dead Center ~ Made of tool steel, hardened and ground. ~ +/- .0002″ TIR ~ Overall length (L) is 3.2″ ~ Height of the notch (h1) is .30″ ~ Widest diameter of the taper (H) is .48″ ~ D is 12.065mm. Made of tool steel, hardened and ground. +/- .0002″ TIR Overall length (L) is 3.2″ Height of the notch (h1) is .30″ Widest diameter of the taper (H) is .48″ ~ D is 12.065mm.