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.

ER8 Collet Clamping Range 4mm - 3.5mm Standard Series with Runout less than or equal to 0.015mm at 4xD, 8.5mm Outside Diameter 13.5mm Long.

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.

The easiest way to determine what type of collet your machine has is to measure the length and diameter of the collet. All collets have a distinctive length and diameter. Use the chart below to determine the correct collet series for your machine.