"With 12 large, roomy compartments with built-in nest bowls and pegs and floor traction, you'll find a healthy flock of purple martins winging your way as soon as you erect this agriculturally themed birdhouse. U.S.A. Mounting Type Pole mount, Dimensions L x W x H in. 22 1/2 x 6 3/4 x 21, UV Inhibitors Yes, Compatible With Purple Martins, Application Bird housing, Capacity 12 room, Assembly Required Yes, Includes Starling resistant doors, Material Polypropylene. Made with UV-protected polypropylene copolymer plastic in a snap-together design that provides drainage and ventilation for dry nests and maximum rain protection Expandable if desired Starling-resistant doors"