Being someone who has obviously done a lot of research and development on this type of setup, I can point out a few potential problems. Like Zeiss said, I have no idea how it's actually hydrated. Also, I tried going with a solid core made of an absorbent material for a while, and #1, you don't get the moisture gradient that you do with a liquid-tight inner tank that only allows water to flow through the bottom and up the thin digging space on the sides, and #2 for the same reason, the water evaporates a lot faster. You essentially just have a box of substrate (ironically the way mine are named).
This type of acrylic container is definitely not the best choice for a dirt nest. Those pieces of acrylic are snapped together and are not going to hold liquids in. I know from experience, that even the slightest crack will slowly start to leak out nastiness, so I can't imagine what will happen on all the corners of this thing. If I'm not mistaken, it even looks like they have an array of holes purposely built into the sides, which is even worse.
BugFinder is right though, there aren't any of mine available right now, and I am not sure when I will have more made. There definitely will be more though. I am actively working on some small upgrades to the design.