The CURT weld-on gooseneck ball is perfect for hardworking trucks and gooseneck trailers. It features a ball diameter of 2-5/16" to fit any standard gooseneck trailer, and it is constructed with high-strength steel alloy. It is also heat-treated to optimize strength and durability to ensure dependable towing and long-lasting use. To allow this gooseneck trailer ball to be ready to weld onto a flat-plate gooseneck hitch, it comes with a raw steel finish. It is also tested to meet VESC V-5 specifications for safe towing.