The ER Series features standard collets which are designed with huge clamping capacity for various drilling purposes.
These are characterized by different collapse ranges such as 1 mm/.040" (ER16, 20, 25, 32) and 0.5 mm/.020" (ER8, 11), an estimated 2:1 grip advantage, and a DIN 6499 Class 2 accuracy.
This series is also available in metric/inch sizes.