CURT Class 3 Ball Mount, Imported (2" Shank, 7,500 lbs., 6" Drop, 12-1/4" Long) Model 45880CURT Class 3 Ball Mount, Imported (2" Shank, 7,500 lbs., 6" Drop, 12 1 4" Long) Model 45880 CURT class 3, or standard duty, ball mounts are a step up from classes 1 and 2. They feature a 2" x 2" shank and have a higher weight capacity for towing heavy duty trailers, including utility trailers, boat trailers, campers, single horse livestock trailers and most recreational vehicle trailers. With class 3 trailer hitches being the most common type of