I saw :shock: one of these in Maryland last summer: http://www.webring.org/l/rd?ring=honeybee;id=47;url=http://www.beecoolventilators.com/ The master keep I was visiting was involved in research. He had test hives on scales. The results seemed very impressive. Since, despite holes, proping lids, etc, I roasted my bees last summer, I am thinking about several things: moving to dappled light (caused other problems in past), building some sort of trellis thing over hives... and I am thinking about these. Talk about hiding the reciepts... Anyone have any experience with these? Is there a cheaper source? Is there a way to build cheap from scratch?