I built one but never got any bats. My kids gave me a store bought one and it doesn't have any either. I don't really know why. Good luck.

Linder's carries them. It can take three years or more if you are in an area with bats to lure them in - you have to have it in just the right place at the right height. Has to be in the rising sun, but shaded all the rest of the day and about 20-30 feet up. I know mine isn't quite high enough, but it's got everything else going for it (on year two...) - we don't have many bats, but my fingers are crossed - they really DO like the boxes once they find them. Also, it needs to be up by the start of April when they migrate back.

-Marie