ER collets are manufactured as per DIN 6499. The accuracies of collets are as per DIN 6499. ER collets are most widely used collets for tool holding in all the types of machine tools & are the most widely used system all over the globe.

ER Collets (DIN 6499) Available in following sizes:

ER 8 (Range 0.5-5 mm; 1/32-3/16 in)
ER11 (Range 0.5-7 mm; 3/64-17/64 in)
ER16 (Range 1-10 mm; 3/64-3/8 in)
ER20 (Range 1-13 mm, 3/64-33/64 in)
ER25 (Range 2-16 mm; 3/64-5/8 in)
ER32 (Range 3-20 mm; 1/16-25/32 in)
ER40 (Range 4-26 mm; 1/8-31/32 in)