Manufactured from a single piece of solid steel with various shank lengths to accommodate a variety of ball platform thicknesses. Rated from Class I to Class IV with varying gross towing loads up to 17,000 pounds.‡ Includes lockwasher and nut. Follow these easy steps to properly determine the correct trailer ball for your application: A. Determine Ball and Coupler Size — Most couplers are stamped with the required trailer ball size. The sizes you'll most likely find stamped in the coupler are: Class I, 1-7/8 inch; Class II, 2 inch; Class III, 2-5/16 inch. B. Gross Trailer Weight (GTW) — Select the appropriate trailer ball to match or exceed the Gross Trailer Weight rating of the trailer. C. Match the trailer ball shank to the ball platform thickness and hole size — when mounted in the ball platform, the threaded ball shank must protrude beyond the bottom of the lock washer and nut at least two threads. D. Hole Size — the trailer ball shank must be matched to the platform hole diameter size. Standard hole sizes are: Class I: 3/4 inch diameter; Class II: 3/4 inch diameter; Class III/IV: 1 inch diameter; Weight Distribution: 1-1/4 inch diameter.