Abstract: Collet includes a housing having a wall with external and internal surfaces, having opposing ends, and having an internal hollow portion with at least one opening; and a flap internal of the opposing ends of the housing in the wall and over part of the internal hollow portion of the housing such that, when a suitably firm force is applied from external to the flap, a suitable object such as a rotary tool bit inserted in the internal hollow portion of the housing through the at least one opening can be held securely in place at least partly inside the housing by the flap. The flap may be provided, for example, by two radial slits which may extend into the wall to coincide with the diameter of the housing and which are connected to one axially directed slit. Seal(s), for example, O-ring(s), may be provided between the flap and either end or both ends of the housing and/or internally between the tool shaft and internal collet wall. The collet can be assembled with a collet holder and rotary bit.