Standard Micro (STD); With Std #23 Seat Plug; Micrometer by Cartridge: 219 / 219 Short (OR) Donaldson Wasp, 219 Zipper, 22 BR Remington, 22 Nosler, 220 Swift, .222 Rem Mag, .22-250, .22-250 Improved 40 Deg., .223 Remington, 223 Rem Improved 40 Deg., and .225 Win; For your seating die; It is directly replaces the original seat plug in your current seating die and adds a higher level of precision, repeatability and flexibility