The Pantheon Arms Castle Nut Installation Tool was designed specifically for installing a Dolos or Prometheus kit on your AR pistol or rifle. This Gunsmithing Equipment from Pantheon Arms is machined to fit the Dolos castle nut precisely. The Pantheon Arms Castle Nut Installer is compatible with 3/8 inch drive ratchets or torque wrenches. For a more accurate installation of a Dolos kit, or when you need to make multiple intalls, use the Pantheon Arms Castle Nut Wrench Tool.