Tapping Adapter, Tap Size 5/16 in, Tap Square Size 6.05mm, Compatible with Product Type TG Collet Chucks, Coolant Fed Non-Coolant Through, Features 0.13mm (0.005 in) Range of Collapse;Grips on Back Taper and Margin of Drill for Maximum Feed Rates and More Accurate Holes;Industry Standard Erickson Single-Angle Collet System;Provides Tremendous Grip (3:1 Advantage) and Accuracy for all Drilling Applications;Slot in Back of Collets Acts as a Drive for the Tap Square