Bluebird Box House Brand_Sloggers Great foraging treat Size:35 lb Great foraging treat Fortified with guaranteed live probiotics to support digestive and immune health Durable rust free galvanized wire meshPredator guard extends entrance hole to protect against predatorsPredator guard entry hole has a diameter of 1 1 2" Predator guard with an entry hole 1 9 16" in diameter for Western bluebirds can be purchased separately on the Replacement Parts page and retrofit to the bluebird houseBluebird house body has an entry hole with a diameter of 1 9 16" to allow it to be used for both types of bluebirdsFledgling kerfs provide extra grip for fledglings to climb out Nuthatches