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.

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.

Standards of ER Collets 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.

ER32 series collets have a capacity of 1mm-20mm. Each ER32 collet has a range of (1 mm). The size indicated on the collet is the largest size it can hold and can be collapsed smaller within its collapse range of (0.9mm). For example, ER32-6mm can grab a round shank from 6mm diameter to 5.1mm diameter.