Hardened precise grinding Designed for high precise and highly-speed applications The length of the extension rod allows the milling cutter to enter the deeply cavity machining grooves for machining Engineered for high precise machining, this collet chucks extension rod features vacuum quenched 40CrMnTi alloy steel with HRC58-62 hardness and 0.01mm pulsation tolerance, ensuring most tool life and nonvibration operate in high speed applications up to 30,000RPM Available in 5 configurations combining straight shank size (8-12mm) C8ER8A/C8ER11A/C10ER8A/C10ER16A/C12ER8A optional, the 100mm extended shaft enables deeply cavity machining while hardened precise grinding maintains <0.01mm runout for professional accuracy, Manufacturer: BULAIDAI