Attract bluebirds and swallows to your backyard with the Nature's Way Cedar Bluebird Box House. This bluebird house is made with insect- and rot-resistant premium cedar and has a water based preservative that maintains color longer and hinders mold and mildew growth. 2 predator guards extend entrance hole to protect against predators, 1-1/2 inch for Eastern and 1-9/16 inch for Western bluebirds. Fledgling skerfs provide extra grip for fledglings to climb out. All hardware is rust free. It has maximum ventilation, elevated mesh base to manage blowflies, predator guards and fledgling skerfs. It is approved by North American Bluebird Society by meeting or exceeding their standards. It comes with a 5 year warranty.