Harlingen ER-16 9mm Spring Collet ~ HARLiNGEN® ultra precision ER collets are made of high performance, special Grade GCrlS bearing steel that has been fully hardened and precisely ground by experienced craftsmen. ~ The powerful clamping ability and durability are ideal for boring, milling, reaming, drilling and tapping as well as grinding operations in high precision machining. ~ Runout is ≤0.008mm. ~ Your choice for secure and rigid holding of drills of any size while retaining the highest concentricity within the range. ~ 8 degree taper design enables maximum gripping power. ~ All slits are spaced and ground evenly. ~ DIN6499B