This wooden bluebird house has a sturdy clear plastic window that prevent disturbing the nest, yet allows you to view and monitor the nest. The plastic will lift out for easy cleaning. The hinged side has a nail lock to keep the plastic hidden until viewing. A predator guard is located right inside the entrance hole to protect the nest. Ventilation and drainage holes help keep the house clean. Made of cedar. Can be post-mounted. American Bluebird Society approved.