Item Type: Shank Router Bit Collet Extension Model: SL12.71/2-ER20 Material: High-speed steel Matching Jacket: ER20 Head Diameter: Approx. 28mm / 1.1in Total Length: Approx. 88mm / 3.5in Tail Shank Diameter: 1/2in Applicable Machine Tool: Lathe Package List 1 x Shank Router Bit Collet Extension 1These clamps are used for 1/2in extension rods and accept 1/2in shank milling cutters for conversion and extension. 2The extension rod eliminates the risk of pulling the shank out of the collet and extends the drill bit to provide a full depth of cut. 3With easy to use, first insert the collet into the cap, then insert the milling cutter into the collet from the top of the nut, then insert them into the rod together, and finally, rotate and fix it with a wrench. 4With high accuracy and smooth cutting, this tool has special impact resistance and good wear resistance. 5The lathe clapimg allows to process products more efficiently, which suitable for lathe processing.