CURT Double Lock Riser Gooseneck Ball, 1-Inch Rise, 30,000 lbs, 2-5/16-In. Diameter Model 60603CURT Double Lock Riser Gooseneck Ball, 1 Inch Rise, 30,000 lbs, 2 5 16 In. Diameter Model 60603 While the basic CURT gooseneck ball offers all the towing power needed for towing that heavy duty flatbed trailer, a standard trailer ball does not always provide the perfect fit for your unique application. The CURT Double Lock gooseneck riser ball offers a quick, easy way to raise your gooseneck coupling point whenever necessary. It uses the same dual pin