How old is your RV? I believe just about all modern 30A RVs have switched to the L5-30, the twist lock adapter. But campgrounds still use the TT-30. So this is the standard cord on newer RVs. But new or old, L5-30 or TT-30, that doesn't make this adapter useful. It would either require a 50A cord if you plug it into the RV, or a L5-30 to L5-30 if you plug it into the campground pedestal. Which no one carries, because no campground pedestals use that socket.

That is a cord that exists and is used for generators though.

I guess what I was really asking was, are there campgrounds with cords built into the pedestal where you don't use use your own cord. Then this adapter would be useful if you need to use the 50 amp cord.