8mm to 12mm Shank Router Bit Extension Rod Collet Engraving Machine Extension Milling Cutter for Wood Features: Made of high-quality carbon steel, sturdy and durable for long life. 8 various types to meet your different needs. Start slowly, wait for the balance to stabilize, then gradually accelerate. High precision woodworking milling cutter chuck that securely fits your engraving machine, ensuring stable clamping and improved work efficiency. Ensure the router collet extension is properly assembled. The extension shank must be securely tightened, and the collet nut should be tightened with the same pressure as any standard router collet. Specifications: Material: Carbon Steel Type: 8 types (optional) - 6mm shank to 6mm shank (A) - 1/4" shank to 1/4" shank (B) - 1/4" shank to 8mm shank (C) - 8mm shank to 12mm shank (D) - 8mm shank to 1/2" shank (E) - 8mm shank to 8mm shank (F) - 12mm shank to 12mm shank (G) - 1/2" shank to 1/2" shank (H) Package Size: 100 x 30 x 30mm / 3.94 x 1.18 x 1.18in Package Weight: 110g / 3.88oz (A, B, C); 135g / 4.76oz (D, E, F); 145g / 5.11oz (G, H) Packing List: 1 x Router Bit Collet Extension