I have a 5 frame obh it has 2 deeps and three med frames. It is like a 1\10 scale hive sorta. I let mine sworm this year. my queen was on here third year. I just wanted to watch how it works out. This obh has tought me more than any thing else i have read or done. Like Brian says you can judge what can happening in the rest of your hives. Obh should be kept by every beekeeper, they are a great tool. Jeff