We have found these pollen traps to be the most productive. They fit under the hive in the position of the bottom board and are highly effective at capturing pollen from foraging bees returning to hive. Easy access drawer allows you to check and collect pollen. Trap entrance can be opened to allow bees unrestricted entrance to the hive. It is recommended to only collect pollen for a few days in a row, so as to not restrict pollen stores in the hives of too much.