ZJchao Precision ER25 15pcs Spring Collet Chuck Collet Set 2mm-16mm for CNC Milling Lathe Made of high grade specially formulated spring steel. Hardened and precision ground. Built in self-release design and tools will never get stuck in holder. Big clampingforce andwide clamping range, widely used in machining centers,general milling machines, CNC milling machine, engraving machine, high-speed machines, and other processing.