JM Part Number Part Max Dia Part Max Flat Max Torque Drive Size Inches Inches Ft-lbs Inches RKW30 0.655 0.535 40 0.375 RKW30M 0.675 0.511 40 0.375 RKW30D 0.675 0.556 40 0.375 Lifetime GuaranteeMade in the USA using AISI 4150 steelExtends the life span of the Retention Knob and Toolholder 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