The 1 1/2 inch hole is ideal for Bluebirds and Finches. Where you place the house will depend upon which bird you wish to house. Bluebirds like their houses next to open meadows or orchards and their house low 5-9 feet off the ground. Finches, particularly the Purple Finch, like dense conifers and their house 8-12 feet from the ground. Your birds will appreciate this unfinished house; no paint, no stains, no plastics. Just beautiful old wood reclaimed from local long gone mills and salvaged New England barns. Each bird house is designed so the bottom can easily be unscrewed and removed for annual house cleaning. Another reason your birds will flock to this house. The hole is 1 1/2" in diameter specifically for bluebirds. Please place at least 5-6 feet from the ground on the edge of a meadow. Blue birds prefer if their house has a southern exposure. This weathered bird house is locally made by an expert wood crafter right here in New England. Outside house dimensions are 11" high (not including the 4" extension of the back board) x 6 1/2" wide x 6" deep.