The standard series are: ER-8, ER-11, ER-16, ER-20, ER-25, ER-32, ER-40, and ER-50. 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.

Collets and chucks are two common types of mechanism used to hold spindle tooling or workpieces. Technically speaking, a collet is a type of chuck, but the two terms are usually used exclusively. A 'chuck' usually refers to any type of work holder which is not a collet.

ER32 Collets- ER32 Standard Collets Our ER32 collets have a capacity ranging from . 0937 - . 7500 inches or in metric sizes from 3mm up to 20mm. The number shown on the collet is the largest size that particular collet can hold, but it can be tightened to a smaller size.