1、Made of high-quality carbon steel, sturdy and durabl-e for long life. 2、8 various types to meet your different needs. 3、Star-t slowly, wait for the balance to improve, you can slowly accelerate. Features: Made of high-quality carbon steel, sturdy and durabl-e for long life. 8 various types to meet your different needs. Star-t slowly, wait for the balance to improve, you can slowly accelerate. High precisio-n woodworking milling cutter chuck can be perfectly combined with your engraving machine to clamp the engraving machine stably and improve work efficiency. Please ensure that the router collet extension be properly assenbled. Please make a note that extension shank should be secured tightly; while collet nut should be tightened only with the same pressure as any 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*30*30mm/3.94*1.18*1.18in Package Weight: 110g/3.88oz(A, B, C); 135g/4.76oz(D, E, F); 145g/5.11oz(G, H) Packing List; 1*Router Bit Collet Extension