Attracts bluebirds, Carolina wrens, yellow-bellied sapsucker, tree swallows and the hairy woodpecker. Height 12in, hole size 1-1/2in x 2-1/4in. Droll Yankees nest boxes are designed with all the right features for cavity nesting birds. Exaggerated roof overhang - keeps rain and sun out, keeping eggs and birds dry and temperatures stable. Unique entry hole replicates a natural tree cavity. Side door - easy access for monitoring and cleaning. Ventilation - under eaves and in the floor, for proper air flow. Kerfs on inside front - help fledglings climb out of the box. Predator guard - increase depth of entry. Correct wood thickness - insulates against heat and cold. Nest boxes are made of pine, a resource that renews itself rapidly so that habitats are quickly restored.