Specification: Metric sys: 2² ~30² , long: 50~200 British system: (1/8")² Long: 4"~10" Material: T1, M2 and super-hard material. Appleiction: Universal HSS TOOL BITS are suitable for cutting metal materials as well as nonmetal materials the other is made from super-hard HSS, which is used for cutting material that of high-hardhess or high-difficulty.