Balance Index Rings, Compatible Taper All Taper, Compatible with Product Type For Fine Balancing of All Tool Holders, For Use With 66mm Shank Diameter, Includes (2) Balancing Rings, Clamping Screw, Overall Length 76.00mm, Shank Dia. 66.00mm, Features Balances Quickly and Precisely, No Damage to the Tool Holder, Simply Fixed by Clamping Screw, The Balancing Machine Determines the Position of the Rings