Features: for Durability Made of Specially Formulated Spring Steel Hardened and Precision Ground Built-in Design and Self-Release Tools Will Never Get Stuck in the RackProduct Parameters:Model: ER11 Optional Specifications: 1MM, 2MM, 3MM, 4MM, 5MM, 6MM, 7MM Material: Premium 45 Carbon Steel Overall Height: Approx. 18mm Outer Diameter (Max): Approx. 11.5mm Clamping Range: 1MM to 7MM (1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm)Fit for metric shank sizes: for example, 1mm ferrule fit 1mm metric shank, 2mm ferrule fit 2mm metric shank Package List: 1*ER11 colletNote: 1. The actual colors of the item may be slightly different from the pictures shown on website caused by many factors such as brightness of your monitor and light brightness.2. Please allow slight manual measurement deviation for the data.