Ultra-Dex Modular Threading/Grooving Head, Serrated, System Size: 1.575 in, Left Hand Cutting Direction, 2.21 in Diameter Minimum Hole, 1.102 in Center to Cutting Edge, 1.575 in Head Length/Projection, Top Notch Clamp Insert, 1.575 in Head Length, Screw Clamp Insert Holding Method