Not sure what you are trying to ask?
This item is not a reducer, so even if I used it on a 50amp line, I'd still need a dogbone to adapt the 50amp line to this 30amp suppressor (which would be directly plugged into a 30amp outlet).
So, now, I would use a 50amp suppressor on the end of my 50amp line and use a dogbone adapter after the suppressor to step down to a 30amp outlet. This would allow me to use the 50amp suppressor on a 50amp outlet, too, without the adapter.
(actually, I am installing a 50amp on-board EMS, so nothing will be at the end of my 50amp line anymore, except a dogbone when on a 30amp outlet)