The CURT 3" tow ball comes with a 2" shank diameter for added structural strength and a raw steel finish, giving it a tough layer protection against the stress of pulling large loads. Whether its commercial machinery, industrial supplies, construction equipment or farming materials, these trailer balls are built to thrive in heavy-duty applications (NOTE: Never exceed the lowest weight capacity of any towing component; i.e. the vehicle, hitch, trailer, etc). Also, to give them an added advantage, CURT 3" trailer balls are heat-treated and feature coarse threads. To make sure our trailer balls are fit to take on the CURT name, we put them through strenuous testing. Not only does this ensure they are capable of performing at their listed capacities, but it also gives you the confidence you need to tow that trailer wherever the highway leads. Our 3" trailer balls are made for performance and endurance and meet U.S. VESC specifications for your safety., 3" TRAILER BALL (2" X 3-1/4" SHANK, 30,000 LBS., RAW STEEL) #40089 Fits 3" couplers and accepts up to 30,000 lbs. GTW. Constructed from high-strength raw steel. Heat-treated for optimum wear resistance. Zinc-plated hex nut and helical lock washer for secure mounting. Tested for safety to meet U.S. VESC V-19 specifications. Limited lifetime warranty (one-year finish, one-year parts). Notes: The mounting platform must be at least 3/8" thick, and the hole size must not be more than 1/16" larger in diameter than the threaded shank.