Wallace Forge Kingpin to Gooseneck Ball Adapter (Model 2085295).Specifications & FeaturesDesign: One-piece machined steel adapter designed to lock into a standard semi-truck fifth wheel.Dimensions: Features a 2-inch kingpin on the bottom and a 2-5/16-inch trailer ball on top.Capacity: Has a gross trailer weight rating of up to 30,000 pounds.Use: Allows you to tow a standard gooseneck trailer using a semi-tractor equipped with a 5th wheel.