It was made from Aspen wood, which along with wood like cedar, douglas-fir, acacia, red wood are all excellent outdoor timbers that are naturally resistant to decay and most are immune to insects. Untreated aspen wood can last up to 50 years, much longer if treated with oils. It rates low on the Janka scale but performs exceptionally as a building material. Aspen also has low permeability so it is naturally resistant to rot from snow, rain, and humidity impregnating the wood. By comparison untreated pine will rot if left outside in about 3 years.