Features: Made of high quality carbon steel, sturdy and durable for long service life. 3 different types to meet your different needs. br/> Start slowly, wait until the balance improves, you can speed up slowly. The high-precision woodworking milling cutter chuck can be perfectly combined with your engraving machine to clamp the engraving machine tightly. stable and improve work efficiency. Please make sure the router collet extension is installed correctly. Please note that the extension rod must be securely fixed; while the collet nut should only be tightened with the same pressure as any router collet. Features: Material: Carbon steelType?: 3 types (optional) ? ? ? shank 1/4" (A) ? ? ? shank 1/2" (B) ? ? ? 8mm shank (C) Package size: 120*70*20mm/4.72*2.76*0.79in Package weight?: 110g/3.88oz(A) 85g/3oz(B) 135g/4.76oz(C) Packing list; 1 * Router Bit Adapter