On Monday, April 28, 2014 4:07:48 PM UTC-5, son_of_flubber wrote:
I wonder what is the actual size of this 50 mm ball? Tolerance is not stated.
I put the calipers on my 2" U-Haul brand ball and it measures 50.5 to 50.35 mm. Some of the chrome is scraped off after towing a Polish trailer for 2000 miles or so.

I will measure the eTrailer 50mm ball when it comes in and report back.