1、5Pcs in 1 Set: Including 5pcs ER11 collet chuck, suitable for CNC engraving machine and milling machine. 2、Standard Sizes: These spring collets have standard size with an inner diameter of 3mm and a wide and stable clamping. 3、Spring Steel Material: Made of excellent spring steel, with good elasticity and tensile resistance, hard and durable. 4、Multiple Usages: Commonly used in boring, milling, drilling, tapping, engraving, spindle machine tools and other processing. 5、Good Performance: These spring collets are small in size, and have fine workmanship, with good elasticity and accuracy. 5 x Spring Collets Item Type: Spring ColletMaterial: Spring steelModel: ER11Inner Diameter: Approx. 3mm / 0.1inQuantity: 5pcsApplication: CNC engraving machine and milling machine