Collets set Material: 45 # steel It is ER11 precision spring collet. Durable and wear-resistant,Large holding force, wide clamping range. Gripping Range: 1mm to 7mm. Widely used in machining centers,general milling machines, CNC milling machine, engraving machine, silver COLOR high-speed machines, and other processing. Style: ER11 Material: 45 # steel Size: Show as in the picture. Gripping Range: 1mm,2mm,3mm,4mm,5mm,6mm,7mm Fits metric shank size(s): For example,1mm Collet Fits 1mm metric shank,2mm Collet Fits 2mm metric shank. Package Included: 7 x ER11 Collet(1-7mm) Only the above package content, other products are not included. Note: Light shooting 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.