Just like the R-8 collets to the left, these are made with the best materials and ground to better than industry standard tolerances. Total indicated runout is less than 0.00059". Made to exact specifications using carefully chosen materials, these collets and sleeves will give you accurate and durable service. Hardened to 55-60 (Rockwell C) on all clamping surfaces and 40-45 on the body spring portions, they are then precision ground to fit your fixture, socket or holder to better than industry standards.