It is a two sided inner cover. During the warmer months, the shallow side faces down and it functions as a typical inner cover. There is a hold in the center which can be used for feeding with a mason jar surrounded by an empty hive body.
During the winter, the deep side is used as a mold to pour sugar candy. This faces down and hive moisture, which usually is a problem in the winter, softens the candy so the bees can feed. This puts the feed at the top of the hive, right were the bees will need it when they exhaust their stored honey reserves.
to make the candy:
Bring 7 lbs. of sugar, 1 lb. of water (2 cups), and 1 1/2 lbs. (about 1 1/8 cups) HFCS (or 2:1 sugar water) to a slow boil while stirring until candy consistency is reached about 220 to 230 degrees F. Take the candy off the heat and stir in a 1 lb. of pollen substitute with a whisk. Pour mixture into a mold and allow to cool.
A mason jar can be used to seal and cover the hole in the center and removed once the candy sets.
Very practical idea, and the design is good, however the execution was poorly done. I was surprised to see that 3 out of the four corners had a defect of some sort. And the center hole was very rough.
I bought one of these last fall to over winter my bees and it worked great with the insulation. This spring and summer I have kept using it and it still works great for all year around because in summer I can take the insulation out and put in a jar feeder and not have to worry about drowning bees. Also when I am not using a feeder it has a small top entrance I can open up to allow the bees to come in threw the top and not have to go threw the brood nest to deposit nectar into the suppers. I havenít had any trouble so far with the bees building comb in it but I guess it could happen. Any way all and all I really like this thing I donít think I will go back to the normal inner cover unless they do start building comb in it. Any way its a really nice gadget