1、WIDE APPLICATION: Suitable for clamping grinding heads on various grinding machines, suitable for repairing and grinding tires. Compatible with most rotating tools used in hardware, hobbies, home, and more. For CNC lathes, cutting tools, and work holding machines. 2、SPRING STEEL MATERIAL: These spring collets are made of spring steel, which is sturdy, durable, stable in performance, and convenient. 3、FINE WORKMANSHIP: Completely hardened, very durable and sturdy, suitable for your long term use; The collet group has undergone accuracy grinding with a total runout of less than 0.0003. 4、HIGH USABILITY: Very suitable for various machining applications, including boring, milling, reaming, tapping, and grinding. 5、5PCS: There are 5 pieces collets in the package in different size that can be used for different situations.