Made from alloy spring steel and hardened to HRC 44-48
Surface on the collet has been specially treated to extend the accuracy of the collet tooling life
All collets are checked its runout individually on 4 contact points by a high tolerance bench marked testing rod
On size 3.0mm and larger the runout is .0003"(0.008mm); under size 3.0mm the runout is .00059"(0.015mm)
This size of ER16 collet has collapsing range of 1 mm; the size of the collet is the largest size it can hold and able to hold anything smaller within the collapsing range