Dimensions: overall 10.5 x 7.5 x 5.5, floor 4 x 3.5 to 4, entrance 1 1/8, center entrance to floor 6. It’s best to position the nest box on a tree or pole 5 to 12 feet high, preferably a pole with a squirrel and predator baffle. Face the entrance south or east in a shaded open wooded area in town or in a rural setting, and make sure there is an open flyway to and from the nest box. Tip - for attracting chickadees to a nest box. - Fill the box with about 2 or 3 inches of wood shavings (not sawdust). Excavating the chips is a natural instinct and found desirable for chickadees.