I've been doing quite a lot of reading up about Bats as know very little about them . I read that boxes should be grouped together for best success so I will be buying three or four. I suppose if the Bats don't like them the Bluetits might . @Kandy I don't think the Bats can get into the roof space - we've been here six years and it's never happened. The Rats got in one year and after numerous failed attempts at persuading them to vacate I gave up and they went out by themselves in the Spring. They just wanted somewhere warm and dry for the winter and luckily they didn't cause any damage.