Specification:ER11 collets: Material: 45 carbon steel Color: silver Overall height: approx. 18mm Outer Diameter (max): Approx. 11.5mm Gripping Range: 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm Feature: Built in self-release design and tools will never get stuck in the chuck. Use with any standard ER chuck to provide coolant through application tools. Each sleeve is well packed in a separate protective container with a label. Hardened and precise ground. Performance stability, high accuracy. to use. Widely used, boring, milling, drilling, silk attack, carving, CNC and other processing. ER11A 5mm extension: Material: Steel Height: approx. 38mm (when lock nut) Shaft hole: 5mm (+0.02mm) need to install heating expansion ER11A nut: outer hex nut 19mm maximum overall diameter High strength and hardness. to use. Package Included: 1 x ER11A 5mm Extension 7 x ER11 Collets Note: Please allow 1-3mm errors due to manual measurement. The item color displayed in photos may be showing slightly different on your computer monitor because monitors are not calibrated same.