Features Firmly Fixed: It can be installed on the back plate and used as a fixture for lathes or milling machines, very safe and reliable. Should be used with a backplate (adapter) to connect to your specific lathe spindle. Standard Size: With a diameter of 100mm, this milling chuck guarantees 0.005 accuracy for stability. Make your products process better, more efficiently, and last longer. Perfect Match: Can be widely used in CNC milling machines, turning tools, engraving machines and other equipment. Mounts to a backing plate of your choice for use on lathes; can also be used as a jig on mills. High Quality Material: High-quality carbon steel material, high strength and hardness, durable, anti-oxidation, and long service life. A suitable backplane must be selected to connect your machine. Easy to Install: Lightweight design, compact size and easy to install. The roll and pinion design is like a three-jaw chuck, operated with the chuck keys. Rolling gears and pinions are precision machined and hardened. Specification: Item Type: Collet Model: ER25-D100 Diameter: Approx. 100mm / 3.94in Accuracy: 0.005 Material: Carbon Steel Application: Used to hold tools.  Package List: 1 x Collet Package List 1 x Collet