ADOPT QUALITY MATERIAL - The er11 collet set is made of high grade specially formulated spring steel, high strength and hardness, heat treated, wear , treated,-proof, in use. EXQUISITE WORKMANSHIP - Professional manufacturing, exquisite workmanship, high reliability. Built in self-release design and tools will never get stuck in holder. 7pcs SPRING COLLETS - Collet must be assembled into the clamping nut before inserting into the chuck, 7pcs spring collets, easy to change, strong clamping force. EASY - Use with any standard ER collet chucks for coolant-thru tool applications, built in self-release design, never get stuck in holder. 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 Collet Model: ER11-1, ER11-2, ER11-3, ER11-4, ER11-5, ER11-6, ER11-7Package List:1 Spring Collet