I have a pollen trap which I haven’t used for about 20 years. Anyway with this one, all you do is replace the bottom board with it, which would work with a flow hive. I got a fair bit of pollen with it. You also get a few legs & wings. You need to close it off during wet weather because the pollen gets damp & goes mildewy.
I used to think that while a colony was above a pollen trap, I wouldn’t have to worry about that colony swarming. How wrong was I, the colony still swarmed. Therefore enough pollen still got through the mesh for the colony to build up to swarming strength.