>Is that the size of the bolt the nut fits? obviously bigger than 3/8".
Yes, a 1/2 bolt fits in a 1/2 hole, the head of the bolt is bigger....
Old wrenches were marked for the size of the bolt (the hole), instead of the bolt's head size(how big the wrench needs to be)....
I wasn't aware, however, that IHC wrenches were included in that group, not really surprised tho...