They have a 4 degree taper which is much less than ER collets that have an 8 degree taper. For that reason, the grip force of TG collets is larger than ER collets. TG collets also have a much longer grip length resulting in a larger surface to grip with.

The "ER" name came from an existing "E" collet (which were a letter series of names) which Rego-Fix modified and appended "R" for "Rego-Fix". The series number is the opening diameter of the tapered receptacle, in millimetres.

Steel-Sealed Collets have a special slotting design that prevents coolant from reaching the collet face. Since the design of the slots prevent coolant leakage, these collets can be used in high-pressure coolant applications.

Collets are used to hold a tool in a central position as it rotates. As the tool is inserted into the collet, the device expands and provides uniform pressure that holds the tool in place. However, if the collet stretches too far, it cannot secure the instrument properly and may lose shape.