Made from White PineMade with eastern white pine – a second-growth tree preferred by conservationists – the construction is durable and sturdy. No paints or stains are used, as they may be toxic to small animals. The house is rough sawn, to give baby squirrels a foothold when they are ready to climb out of the nest. The exterior will weather to a natural gray, to blend with its outdoor surroundings.Well InsulatedThe wood is one inch thick for insulation, both from summer heat and winter cold. It is also light colored, to keep it cool in summer. Ventilation is provided at the top of the sides as well as in the four bottom corners. These bottom holes also provide drainage. The side tilts out for easy cleaning of the house, which should be done before each new spring nest. A latch at the bottom holds it securely in place. Shipping: There is an additional $3 shipping charge due to the weight of this product. Sorry, expedited delivery not available on this product.