Router Collet Extension for 1/4" Bits, 1/2" Bits, 8mm Bits; Must be tightened with a wrench to prevent the bit from falling out. Constructed of heavy duty steel for long life, convenient to use. Eliminates the dangerous temptation to remove the shank from the collet and extend the bit to reach the full cutting depth. Make processing products more efficient, suitable for woodworking, milling and engraving machines. Package Includes: 1 x 1/4" Router Collet Extension, 1 x 1/2" Router Collet Extension, 1 x 8mm Router Collet Extension. Size: 1/4 Shank + 8mm Shank + 1/2 Shank Collet Extension Function: This collet extension is made of industrial grade material, high precision, strong and durable for long service life. This milling chuck provides the extra cutting depth needed for many milling tasks. Easy to use, better to control, will improve your work efficiency. Use it to achieve a full depth of cut when machining dovetail serrations, ideal for your woodworking needs. Collet Extension