For TaperCAT 40 Thread Size5/8-11 Angle45ºHead Diameter0.589 Neck Diameter 0.392 Hole (Diameter)Y (0.200)L10.9880 L21.264 O-RingsN Socket Part # RKW40 Machine*Haas, Johnford * Retention knobs are not interchangable. Machines are only given as a reference, JMPP makes no guarantee this is the correct knob for your machine. Please call us at 1-800-322-7750 or email sales@jmperformanceproducts.com for knob identification help. WARNING: The steel alloy used in this product contains chromium and nickel. This product can expose you to chemicals including chromium and nickel, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov