Side flips open for observation and easy cleaning and is held closed by an L hook. The 3/8" ventilation slots between the walls and roof keep the house from overheating. Drainage holes in bottom corners keep the nest dry. Made from eastern white pine for insulation and durability. Dimensions: 7-1/2" W x 7" H (plus 7" hanging chain) x 7-1/2" D. By Coveside Conservation Products.