CURT Stainless Steel Trailer Hitch Ball, 3,500 lbs, 1-7/8-Inch Diameter, 1 x 2-1/8-Inch Shank Model 40081CURT Stainless Steel Trailer Hitch Ball, 3,500 lbs, 1 7 8 Inch Diameter, 1 x 2 1 8 Inch Shank Model 40081 CURT 1 7 8" trailer balls are constructed from high strength steel to match the towing power of your class 1 or class 2 trailer hitch and ball mount and come with fine threads on the shank for improved holding strength. Having a trailer ball that matc hes your coupler size is absolutely essential. At CURT, we engineer our trailer balls to be