Looked at the link you gave, great pictures for everyone to see what we're talking about, thank you.
You all are not going to believe this! I just had a major brain flash. That grab nut fits a 12 or 6 point box wrench perfectly. So it must be 12 points not 14. That grab nut is also the same size as the adjusting hex on the threaded rod so the box wrench fits right over it.
I suspect the grab-nut looks different than an normal nut with flats because it had to be formed onto the end of the push rod which has only a thin wall.
By the way, on my booster these are 7mm wrench size.
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