You need two of the small ones for an entire DCX set, but they work well and stack nicely. They are made well, but I wouldn't want to drop one on the floor.
I don't have almost any sets that fit in this box, at least not entirely. If I have most of the keycaps on a board, it can fit some, but it doesn't have space for much at all. I bought the smaller of the two, but I was shocked how small it was.
Solid plastic, very clear, but I would suggest be gentle or it might break in the middle since it's so big. The keycaps fit well within the rows and you can slide them around as needed. Do not flip or tilt it too much as there is a lot space on top so depending on your keycaps profile height they could fall out and around. Also, near the edges it gets tight and you may need to squeeze your caps in there.
Otherwise nothing much to complain. Pictured is my DCX Lunar New Year set in it for your reference.
This tray (1) fits MT3 profile keycaps and (2) is large enough to store a base set with a couple of extra sets. However, the tray feels flimsy and the latches aren't stable. Most trays of better quality as smaller, but I'd rather have two of those than one of these.
Got a pack of Max storage trays, mostly to organize keycap sets that came in bags or had lots of extra keys.
Even though it did its job with the most of my stuff (Cherry / MT3), the Max version doesn't work that great with DSA or low-ish profile keycaps: there is a lot of height to accomodate potential SA / MT3 caps, so the carefully organized and ordered low keycaps went leapfrogging in their rows. Had to use bubble wrap strips to create a buffer to keep them in place (though it makes it worse for a showcase scenario).
The Standard option is lower (= less wiggle room), but it can contain just a base set. So the ideal solution for DSA would be to have a low-profile version of a Max, though it makes it a fairly niche product.