●Made of high quality specially formulated spring steel, high strength and hardness, heat treated, wear-resistant, surface treated, rust-proof, durable in use. ●Professional manufacturing, exquisite workmanship, high reliability. Built-in self-release design and tools never get caught in the holder. ●Collet must be installed into the collet nut before inserting into the chuck, 7 piece collets, easy to change, strong clamping force. ●For use with all standard ER collet chucks for coolant applications through the tool designed in a self-release design and never get caught in the holder. ●Widely used for drilling, milling, drilling, silk attack, sculpture, CNC, and other processing.