That expalins it all. Since he doesn't really have a left, and that's where the caliper goes, his legs don't have a caliper mount.
He has 100% positive feedback. If he wants to preserve that he may want to rethink his sale. I think I'll tell him. Honest mistake from someone who doesn't know better. I assume.
He does say in his description they fit a 1980 CB750A. But that's not quite right either I guess.