Take an extra step to safeguard your birds against predators with the Lone Star Slant-Front Bluebird House. The tapered design makes it easier for bluebirds to build their nests, because this shape requires less nesting material. A slanting roof and inside drainage holes also guard against rain. Other features include ventilation holes that keep the house from overheating and harming baby birds and a rough interior that enables fledglings to climb out of the box. Lift the front panel for easy seasonal cleanouts. Mount this bird house to a post or tree to entice beautiful, musical, scarce bluebirds to your yard. This Bluebird Nest Box is a modified design of the very popular Peterson Bluebird House. Opening: Oval 2.25 inches long x 1.38 inches wide. Dimensions: 14 inches long x 5.5 inches wide x 6.5 inches deep.