... clamping ability 4.Hardness:HRC44-48 Products Features:ER Collet With Excellent quality,ER 11 Collet1.Made of special Elastic steel material ... ability, presise accutacy.3.Runout: 0.005mm-0.015mm4.Used for boring, milling, drilling, tapping, grinding and engraving operation etc.5 ... in China. We can suplly various machinery accessories such as Er collet, Sealed collet, Tap collet, R8 collet, 5C dollet, ...