What is the underlying concept of the slatted rack and how does it work? As I recall, C. C. Miller came up with this idea while trying to figure out how to improve ventilation in his hives. He raised comb honey using one brood box, as I recall. I think a lot of people in those days would raise the hive up on little blocks to increase the air flow into the bottom of the hive, but as you can imagine, the bees would build a lot of comb in that space (what a mess). So, Miller hit upon the idea of a very deep bottom board with this rack in there to prevent the build up of burr comb in the space below the frames. As many people know, I am not a big booster of screened bottoms, but in my opinion, this is one thing they are good for: increasing the ventilation at the bottom of the hive. I would choose one of these over the slatted rack bottom. I think it is more effective and cheaper and easier to build. pb