6 PCS ER20 Collet : 3mm / 4mm / 6mm / 8mm / 10mm / 12mm. Collet Chuck Material: 65Mn. Collet Chuck Precision: 0.015mm. Use with any standard ER collet chucks for coolant-thru tool applications. Usage : The motor shaft extension rod sleeve on the motor shaft, and both sides of the screw is tightened.
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