Consists of 2 story, 12 room single house. Converts from 12 single to 6 double rooms to better accommodate larger colonies. Front panels open for easy access and cleaning. Starling resistant entrance holes. Constructed of rust-free heat-dispensing aluminum. Sturdy construction for years of use. Guard rails to protect young martins. Special features: simply remove interior plug and slide solid door in place to convert from a single to double-sized apartment. Perfect for the growing martin colony. Made In U.S.A.