This double beehive screen is also called the Snellgrove Board. The double screen isolates the bees that are above from the bees that are below the screen, while still allowing heat to circulate in the hive. By manipulating the three different double entrances, one can add or subtract bees from the top or bottom, or run a split on top of one parent colony. Can also be used to increase hive population and foster swarm control. Comes fully assembled with screws for durability.