Collets set Material: 45 # steel It is ER11 precision spring collet. and wear-,Large holding force, wide clamping range. Gripping Range: 1.0mm-7.0mm & 1/4 inch , 1/8 inch Widely used in machining centers,general milling machines, CNC milling machine, engraving machine,high-speed machines, and other processing. Color: Silver Material: metal Package Contents: 1 x 1mm Spring collet 1 x 1.5mm Spring collet 1 x 2mm Spring collet 1 x 2.5mm Spring collet 1 x 3mm Spring collet 1 x 3.5mm Spring collet 1 x 4mm Spring collet 1 x 4.5mm Spring collet 1 x 5mm Spring collet 1 x 5.5mm Spring collet 1 x 6mm Spring collet 1 x 6.5 mm Spring collet 1 x 7mm Spring collet 1 x 1/4 inch Spring collet 1 x 1/8 inch Spring collet Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.