Item Type: Collet Model: SKER89PC01 Material: High Speed Steel Accuracy: 0.005mm Specification: Approx. 1mm / 0.04in 1.5mm / 0.06in 2mm / 0.08in 2.5mm / 0.1in 3mm / 0.12in 3.5mm / 0.14in 4mm / 0.16in 4.5mm / 0.18in 5mm / 0.2in Package List 9 x Collet Generally, the collet is marked with the number of the clamping diameter, such as 5, which means that the clamping diameter of the collet is 5mm. 19Pcs in 1 Set: Comes with 9pcs collet in different sizes, which will satisfy your various working needs. 2Stable Working: Has high elasticity and great resistance to tension to ensure stable work performance. 3Firm Clamping: International opening standard enables firm clamping without slipping, safe and reliable. 4Good Material: Forged with high speed steel, not easy to deform or crack, rustproof in long term using. 5Practical Use: Allows for wide application in CNC, engraving machine, milling lathe, etc., very useful.