R8 Shank Drill Chuck Arbor Inch to Jacobs Taper. Precision ground, Made of high quality Steel, Used in Machining applications. Taper Mount and Taper Shank. Shank to Taper Runout <0.0001". HIGHEST ACCURACY: Precision Ground HIGHEST TOLERANCE: Taper to Shank Runout < 0.0001" Shank Taper: R-8 Mount Taper: Jacobs Taper HIGH QUALITY STEEL: Made of High Quality Hardened STEEL.. China Manufacturer 100% Guarantee to be Free from any Manufacturing Defects. 100% Customer Satisfaction Guarantee