They worked fine from side to side on a straight pull, but not at an angle. at least mine didn't Unless using a side kit, I saw no advantage other than time consuming at all for them.
Between D-rings and chain pop ups, 36 pair in my 42 foot spread. Not all flats have stops welded in the floor for j hooks.
Mine had no stops, it would have been better if it would have had them for sure. I originally bought it to haul big bales of hay, because it was light. J hooks were worthless for that, I pulled it on a few freight runs, then just got rid of it when I quit the hay business.
