This is a tandem axle Square Aluminum Diamond Plate Trailer Fender. Aluminum Dual axle trailer fenders are most commonly found and sold for Boat Trailers. The Aluminum Construction is completely ideal for boat trailers because the fender is lightweight, durable, and will not rust! We have these available in many sizes so check the specs in the picture and be sure this one will work for your boat trailer. these are commonly seen protecting 13 inch to 15 inch trailer tires. Typically replacing a boat trailer fender means a tire blew out or the old fender rusted through. Keep in mind when doing this project you may need additional hardware to complete the installation.