ZJchao 13 Pcs ER11 1-7mm Spring Collet Set Chuck Collet for CNC Engraving Machine & Milling Lathe Tool 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 clamping force and wide clamping range, widely used in machining centers,general milling machines, CNC milling machine, engraving machine, high-speed machines, and other processing