However, the collet is most often used in routers to hold the cutting bits in place. The collet is secured to the tool using a hexagonal collet nut, allowing it to be tightened or loosened to the motor arbor.

ER collets: These devices are often considered the best choice for manufacturers when it comes to clamping devices. An ER collet is a CNC tool used to hold various components used in mills. These devices consist of the main body and a threat end. The nut screws onto the main shaft.

These collets are usually found in a standard series as: ER-8, ER-11, ER-16, ER-20, ER-25, ER-32, ER-40, and ER-50. The numbers represent the opening diameter of the tapered receptacle in millimeters.