Item Type: Milling Cutter Accessories Extension Rod Material: Carbon steel Extension Rod Diameter: 1/4in ER16 Collet Diameter: Approx. 3.5mm / 0.14in, 6.5mm / 0.26in ER16 Spanner Length: Approx. 12.5cm / 4.9in 1Milling Cutter Accessories: The milling cutter accessory kit includes router bit extension rod, ER16 collets and mill holder spanner, etc. 2For Trimming and Milling: Commonly used in milling machines and engraving machines, can be used for wood trimming, milling, etc. 3Carbon Steel Extension Rod: The router bit extension rod is made of carbon steel, which is resistant to wear and deformation. 4Extension Rod Function: The extension rod eliminates the risk of pulling the handle from the chuck and provides a complete cutting depth. 5With 2Pcs Chucks: Contains 2 sizes of 3.5mm and 6.5mm ER16 collet chuck, suitable for different clamping scenarios.1. Please make sure that the ER chuck extension is installed correctly; please note that the extension handle must be firmly fixed; and the chuck nut and the extension rod must be tightened. 2. Due to manual measurement, please allow a difference of 1?3mm. 3. When processing materials, speed up slowly first, and then speed up processing after waiting for stability.1 x Extension Rod 1 x ER16 Spanner 1 x ER16-6.5Collet 1 x ER16-3.5Collet 3 x Storage Box