ITEM NAME:8mm/ 12mm Shank Bit Router Collet Extension Rod for Engraving Machine Tools 80mm Description: High precision, stable performance. High strength and hardness. Durable and practical to use. Make you more efficient to process products. Suitable for automobile manufacturing, mold manufacturing, machinery manufacturing and so on. Specification: Material: Hardened Alloy Steel Overall Length: approx.80mm/ 3inch Shank Diameter(for your chose): 8mm(5/16''),12mm,12.7mm(1/2'') Color: as picture shown Package Includes: 2 Pieces Extension Rod Note: Please allow slim measuring error due to manual measurement, make sure you do not mind before you.2 Pieces Extension Rod. High strength and hardness. Make you more efficient to process products.