[Nick Noyes]

We have them on all our lids in the center on both ends. Lets the moisture out. There is very little condensation under the lid even when its cold and wet.

 

[Ben Brewcat]

Tim at honeyrunapiaries.com has plans for a hive top ventilation box... I use it on my colonies with solid bottom boards and love them. No bearding and colonies seem to thrive. I tried one with a SBB also and I think it was WAY too much ventilation, but if you have solid bottom boards and haven't yet switched, try a top box.