Features:Made of high grade specially formulated spring steel, durable in use.Professional manufacturing, exquisite workmanship, high reliability.Built in self-release design and tools will never get stuck in holder.Use with any standard ER collet chucks for coolant-thru tool applications.Widely used for boring, milling, drilling, silk attack, sculpture, CNC, and other processing. Specification:Condition: 100 Percent brand newSpring Collet Model: ER11-1, ER11-2, ER11-3, ER11-4, ER11-5, ER11-6, ER11-7Package List:1 Extension Rod7 Spring Collet