SafePack
The box holds two rows of cassettes, as shown in the picture. However, the box is just wide enough that there is a ~0.5? gap between the two rows, which allows them to move a little too freely. For that reason, I would have preferred some sort of barrier through the midsection of the box. Aside from that minor issue, the box seems very sturdy and suitable for stacking, and is the perfect height (just a bit over 3?) to store cassettes efficiently.