ER20 series collets have a capacity of .015-.512 inches. Each ER20 collet has a range of .039 inches(1mm). ER20 collets .094 and smaller have a range of only .015 inches. The size indicated on the collet is the largest size it can hold and can be collapsed smaller within its collapse range mentioned above. For example, ER20-1/4 can grab a round shank from .250 diameter to .211 diameter. Please refer to our ER20 Collet print for general ER20 dimensions.
