Features DEEP PROCESSING: The CNC router holder with straight extension handle is suitable for deep processing and offers great convenience. R8 THREAD: This R40 tool holder is used for R8 collets, with a maximum speed of 8000 rpm, the drawbar end is 7/16 20. HIGH HARDNESS: The milling shank holder is made of 40CR material, multi-hardened and forged, with very high hardness and stable structure. IMPROVE EFFICIENCY: The collet holder uses fewer extension tools, reducing costs and improving efficiency. HIGH PRECISION: The milling cutter holder is made with high precision through fine processing, which makes the lathe work more precise and reliable. Specification: Item Type: Milling Tool Holder Material: 40Cr Model: R8 ER40 (7/16 20) Shank: R8 threaded shank Drawbar: 7/16 Application: R8 special machine, R40 tool handle Total Tightening Accuracy: ≤0.005 Rounding: 0.8 mm Surface roughness: >0.8 mm Runout Tolerance: 0.0004 inch Standard speed: 8000 rpm per minute Package list: 1 x Milling Tool Holder 1 x storage box Package List 1 x Milling Tool Holder 1 x Storage Box