Nature's Way Bird Products BWH4 Bamboo Bluebird Viewing House Air vents allow for maximum air ventilation through wall and floor openings Clean-out doors provide easy access for cleaning, and stay-clear crack resistant viewing windows allows for viewing while protecting the young Elevated mesh floor aids in management of blowfly, and Fledgling skerfs provide extra grip for fledglings to climb out Predator guard extends entrance hole to protect against predators - 2 included: 1.5-inch for eastern and 1.6-inch for western blue birds and tree swallows Exclusive 10-Year Warranty