High Precision Spring Collets, Extensions, Adapters Holders and Retaining Studs for CNC Machines are made by Amana Tool, the leading manufacturers of cutting tools. All spring collets are inspected for quality & 100% accuracy. Amana Tool CO-424 1/4 Inch Collet for ER11 Nut allows to reduce the vibrations on the tools and motors, assures better results and prolongs the life of the tools and electrospindles. SPECIFICATIONS: (D) Diameter: 11.5mm; Overall Length (L): 18mm; Collet Standard: ER11; D1: 9mm; B: 2mm; (d) Shank: 1/4.