Hitch ball 2". Shank is 1" diameter and 2-1/8" length. Capacity is 7,500 lbs trailer weight.
A37 can be used with a class III or IV hitch system. Note: A hitch system is only as strong as its lowest-rated component. Compare the maximum tow weight ratings of your hitch, ball mount and hitch ball. Your hitch system rating is the lowest weight rating among those components.
Our hitch pro writes: "A37 2" ball is stainless steel."
One of the towing vehicle requirements for this trailer, noted on uhaul.com is: "Must have 1-7/8" or, 2" hitch ball (2,000 lbs. minimum)."