~ Made of high quality tool steel. ~ Hardened and precision ground to highest concentricity. ~ These collets are closed by being drawn back into the collet seating by means of a draw bar. ~ The collets only open a minimal amount. ~ The W10 collets differ from the other pull-type collets because of their external thread, which has a nominal diameter almost identical to the collet shank diameter. ~ The pull-type collets generally only clamp the nominal diameter. ~ To obtain optimal concentricity, it is recommended not to clamp less than 0.1 mm below the nominal diameter.