The boxes we made for Time Breaker (and ChronoTrek) fit in the same display as all our other boxes (holding 2 decks side by side) but only four per display, so they're1.5x taller than our regular boxes. Since this is such a handy size, we had some extras made without any printing. Note that the image is just to show the size of the box. It does NOT come with any cards.
It holds two 130-card decks comfortably. As you can see from the picture, it's more than tall enough for a Fluxx deck on each side (100 cards), but not quite tall enough for a Chrono deck (140 cards), so it's a bit of a squeeze for an UberChrono plus expansions, but doable. There's no insert to keep the two decks separate, but it would be pretty easy to make something out of cardstock.