[ steel]Chuck holder is manufactured by steel which has high hardness and a long service life [55-58 hardness]Lathe tool holder is with high hardnessduring 55-58 after quenching and hardening, will not easily deformed [for inner hole type]Fit for inner hole milling cutter, such chuck holder is manufactured via hardened treatment [1~20mm / 0 04 ~ 0 79in]The clamping range of this chuck is 1 ~ 20mm / 0 04 ~ 0 79in, can be widely used [widely used]Such kind of collet chuck holder is adaptive to various machine tools, such as milling machine, CNC tools Specification:Item Type: CNC tool holderApplicable Machine: Milling machineSpeed: 30000 rpmWhether Coated: Non-coatedTail Hole Diameter: Approx 12mm / 0 5inColour:silverMaterial:steelSize:138 x 27mmPackage Contents:1 * CNC Tool HolderOnly the above package content, other products are not included Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing The measurement allowed error is +/- 1-3cm