I wonder if anyone is familiar with the construction of the above device? In german it is called "Baurahmen" and enables the beekeeper to see activity on the comb without opening the hive. According to H.Storch in his book "At the Hive Entrance" it is widely used in Germany, but unfortunately the only description he provides is, " the glass pane of the window is arranged facing towards the inside of the hive (in Winter) and the free space filled with corrugated paper for insulation. ...In the summer, the building frame is positioned with a starter strip of foundation, and then the window galss outside>" I cannot envisage how this is constructed as to simply replace the side of an existing super with glass will be of no use to observe activity in the winter time. Peter Wright