I tried six of the slotted racks when I was producing cut comb honey. They did not seem to make any difference in production. The hives that have them don't cluster as much on the front of the hive in hot weather as do their neighbours with ordinary bottom boards. They might pay their way in a hotter climate than ours, but they are probably not worthwhile here. Donald Aitken 11710-129 Street Edmonton Alberta Canada T5M 0Y7