This single nesting box is made of high-density, impact-resistant polyethylene that is easy to keep clean and will not rust, rot or corrode. Mounts securely on wall with slide type screw holes. Sloped roof prevents roosting. Mounts to 16" on center studs. Ventilation holes for fresh air. Perch gives hens a place to land before entering nest. Does not get as cold in winter months. Can be mounted vertically or side by side. 16.5"L x 15.88"W x 19.75"H.