The Attwood 113151 Boat Trailer Spool/Keel Polymer Roller is a durable and lightweight accessory designed for boat trailers. Made with a polymer material, this roller is 4 inches in size and weighs only 0.55 pounds. The manufacturer part number 11315-1 indicates the specific model, making it easy to identify and purchase the correct product. With dimensions of 3.78x2.99x2.44 inches, this roller is suitable for various boat trailer sizes and provides smooth and secure transportation for boats.