This insert is intended for use with the Oneway Talon Chuck System (pictured, sold separately, Rockler #20761). Adapts the Chuck for use with your specific lathe (consult your owner"s manual). Three inserts are available: * 3/4" X 16 Tpi Insert (Rockler #22733) * 1" X 8 Tpi Insert (Rockler #22726) * 1-1/4" X 8 Tpi Insert (Rockler #21358)