JM Part Number Part Max Dia Part Max Flat Max Torque Drive Size Inches Inches Ft-lbs Inches RKW40 0.944 0.755 40 0.500 RKW40M 0.894 0.711 40 0.500 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