This collet size is true imperial fractional size, not a metric converting size and the surface on this collet has been specially treated to increase its tool life.
★HIGH HARDNESS: Made of high-quality alloy spring steel and hardened to HRC 44-48 and all critical surface is precision ground.
★TRUE DOUBLE ANGLE for Better Accuracy, the runout is 0.0003" for size 1/8" and larger, and 0.00059" for undersize 1/8".
★UNIQUE FEATURE: The inner structure of the ER32 collet nut is deliberately crafted with an eccentric layout, facilitating the effortless installation of the ER32 collet.