Make any HO Scale building a cool model with these detailed roof-top air conditioners. Since the 1930s, units like these have been installed on commercial, industrial and public buildings. In addition to cooling air, they also control humidity and remove dust and other materials, which makes them essential to modern manufacturing plants. The finished models are an easy way to detail and modernize any structure with a flat roof. And you can combine kits to detail larger buildings, which usually require several to provide adequate cooling for the entire structure, or to serve specific areas inside. Each kit consists of detailed plastic parts simulating a variety of equipment.