This is a factory original replacement G5 core.  This is the latest generation (G5) core.  The core of the Renewaire unit comes with a factory 10 year warranty.  If the core has been properly maintained, it will not need to be replaced.  The only times when it should be replaced is if it has mechanical damage or if it got wet and there is mold or mildew on it.  Under normal operation of the unit, neither of these situations should occur, so in most cases the core doesn’t need o be replaced.