Our rack is placed over the bottom board and is intended to be left on year round. First designed and introduced by Dr. C.C. Miller, slatted racks can be beneficial in a number of ways. Ventilation: The slatted rack places a layer of air below the brood box, which can be beneficial in both summer and winter. In the summer the bees will gather in the space provided by the slatted rack, fanning their wings to move air through the hive. As well as providing them with a greater space in which to fan air through the hive, these bees will be outside the main hive, which reduces congestion in the brood nest area. In the winter, the air space within the slatted rack serves as a dead-space insulating layer, providing some protection from cold air flowing into the hive.