I purchased this for my airplane but never installed it as we ended up going a different route with alternators. This kit is designed to eliminate the issue some newer aircraft have with intermittently tripping the overvoltage relay causing the alternator to go offline. This includes the Beech "kit" 36-3034-0003 which is a set of drawings/instructions on how to build the capacitor with locally sourced parts and a serialized logbook entry sticker. In addition I sourced the capacitor and other parts per the drawings and assembled one capacitor and have an additional capacitor and tubing to assemble another. Asking $150 shipped, but open to offers as I have no use for it.

Does this work with the 12 volt system or only the 24 volt?

I believe this is for the 24V systems only.