The TANDEMKROSS Krossfire Bolt is designed to accept TANDEMKROSS internal components and function in factory Ruger® Mark IV™ and Mark IV™ 22/45™ Compatibility with aftermarket is not guaranteed. The Krossfire Bolt can be made compatible with factory Ruger® Mark III™ and Mark III™ 22/45™ if the user removes the factory Loaded Chamber Indicator or when paired with the Tandemkross LCI Replacement (discontinued).