250-500cc '08 wr 250 fork help

does anybody know the size wrench needed for the blue nut at the top of the fork piston rod that connects it to the fork cap?

my tuner tightened it down super tight and my method of squeezing a crescent in between the springs isn't working as it's an off angle fitment. i'm hoping to pick up the appropriate size wrench on the way home from work but forgot to mic it before leaving the house.

thanks in advance.

14mm rings a bell with me

nah, it's over 17mm. i know that because i tried to throw a wrench on it at first and the 17 was too small so i went back to the crescent because i knew i'd used it before.

19mm