If you really want to attract bats to your property, our large bat house is the way. Holds up to 400 bats, a nice bats habitats.
Bat studies have shown, size does matter. Our large bat house is approximately 32'' high and the inside bat chambers are 11 1/2'' wide by 24'' long.
This bat house has 3 chambers each slightly less than an inch wide. On one side of each chamber it has attached a mesh material that will aid the bats in holding on. It has a large landing area, ventilation gap in front and hanging hardware. The exterior is made out of thick pine, the interior chambers are made out of exterior grade plywood. The house is NAILED, GLUED and CAULKED for strength, durability and to eliminate draughts. Bats are sensitive about their body temperature and will move around the house to regulate it, they do not like draughts.

Visit here for information on bat houses placement.