Sony BE-7H and BE-9H cassette erasers. What’s the diff between the two?

I have a heap of used cassettes and thinking I might blank them out, I know a deck will do it when recording but I was thinking that I just might have them sitting all fresh and new (kinda) .

Anyway, who knows the difference between these two cassette erasers, they both seem to look the same, both seem to erase the same so what gives?

Is the 9H more powerful, or is there any difference in the erasing side. Looks like 9H has an adaptor for micro cassettes, no idea if the 7H has that (not that it’s something I’d need anyway)

Who here knows anything about these, apart from a YouTube video?