Our bird houses are made from exterior grade marine plywood, are fully functional and are designed for outdoor use. Small holes prevent predators gaining access to the nest. Ours are 32mm, which will attract smaller birds such as wrens, tits, and nuthatches. This is essential in prevention of the spread of disease. The birdhouses/feeders will deteriorate in appearance after a year or so like all natural materials but will continue to operate as a birdhouse for many years of weathering. A wood sealant spray can be used (exterior only) to help protect the finish. All information is on the product hang tags. Features: Internal climbing ladder for fledglings to leave the nest Shingled roof Mounting bracket Specifications: Dimensions: H:20 x W:13 x D:14.2 cm Weight: 1.0 kg Colour: Blue Material: Ply-board Model Number: HBD-2003