The Quadex power core was the main power core of the Corellian Engineering Corporation's YT-1300 light freighter. It made use of a hypermatter annihilator, and so was much more powerful than the portable chemical, fission and fusion reactors used in domestic devices.
Energy from the power core was routed to the YT-1300's propulsion units by a progressive combustion reaction power converter, located in the freighter's number three hold. The power core was housed within the YT-1300's central hub, the most protected area of the ship.
The Quadex power core of the Millennium Falcon had undergone modifications to accommodate the ship's numerous customizations, including feeding power directly to the Falcon's AG-2G quad laser cannons. However, its general appearance was otherwise similar to when it was brand new. It had also been retooled long before Lando Calrissian, the Falcon's owner before Han Solo, had acquired the ship.