A collet is a specialized clamping device, typically used in machining and tool-holding applications, that forms a collar around an object—such as a tool shank or a workpiece—and exerts a strong, even clamping force when tightened.It is usually a segmented sleeve, band, or collar made from spring steel or another durable material. One of its radial surfaces is typically tapered, while the other is cylindrical. The collet fits into a matching tapered socket or chuck. When tightened, the collet contracts (or expands, in some internal collet designs) to grip the object securely and evenly around its circumference.

