These locomotive train air horns are constructed from the most durable automotive materials available including heavy duty fiberglass reinforced ABS plastic, stainless steel, and brass. These horns are crafted to meet rigorous standards in the USA. The diaphragms are stainless steel and will never rust! They are built rugged, compact, and lightweight and are the perfect fit for any project. If that wasn't enough their size is much smaller than you'd expect. With the longest horn being roughly 20 inches long and the bells only 5 inches in diameter, these horns can be mounted just about anywhere.