Made with the highest quality cedar, which weathers well and retains heat. The Organization for Bat Conservation house is fully caulked and offers a longer design which is a key factor in occupancy. Thinner chambers and a predator guard give protection. The inside is covered with a polyethylene mesh to aid in maneuverability and there is an extra long landing platform. Proper bat house design is a very important factor in occupancy. Our bat houses have a greater than 80% occupancy rate. The Extra-large bat house may even have a higher occupancy rate than the Single or Triple bat house because of its large size.Extra-large bat houses are great for apartment buildings and large areas (more than 5 acres). Holds up to 600 bats. Comes with mounting instructions.