Features Good clamping force: tension nut holders have a stable structure, excellent performance and long service life, which you can use with confidence. For rotary machines and milling machines: Collet chuck can be mounted on the base plate of your choice for use on a lathe, also suitable as a chuck on a milling machine. For CNC engraving: collet chuck is suitable for CNC milling machine rotary tool engraving machines, not easy to slip, very stable. DURABLE CARBON STEEL - Made of excellent carbon steel material, has a strong antioxidant capacity and high hardness. Guaranteed quality: manufactured according to standard production to make your products better, more efficient and durable. Specification: Item Type:Collet Chuck Model: ER40 (7 holes) Size: Diameter: approx. 80 mm/3.15 inches. Accuracy: 0.005 Material: carbon steel. Package list: 1 x Collet Chuck Small note: Before inserting the collet the collet must be mounted into the collet nut. Package List 1 x Clamping Collet Chuck