Features: Made of high-quality carbon steel, sturdy and durable for long life. Three various types to meet your different needs. Start slowly, wait for the balance to improve, then you can slowly accelerate. High precision woodworking milling cutter chuck can be perfectly combined with your engraving machine to clamp the bit securely and improve work efficiency. Please ensure that the router collet extension is properly assembled. Note that the extension shank should be secured tightly; while the collet nut should be tightened only with the same pressure as any standard router collet.Specifications: Material: Carbon Steel Type: 3 types (optional) - 1/4" shank (A) - 1/2" shank (B) - 8mm shank (C) Package Size: 120 x 70 x 20 mm / 4.72 x 2.76 x 0.79 in Package Weight: - (A) 85g / 3 oz - (B) 135g / 4.76 oz - (C) 110g / 3.88 oz Packing List: 1 x Router Bit Adapter