Mont Bell Hypalon Rain Pants, S?

This is as much an exhibit as a listing: These are early, probably 1970's, Mont Bell waterproof pants using Hypalon coating. I know Hypalon from river trips, where it still used in premier inflatables, but I never knew it was used in outdoor clothing, as well. I'm certain that these don't work as well as modern rain pants, but given how good some of my other Mont Bell gear works, I'm certain that these were better and more innovative than anything on the market in 1976. Anyway, thanks for looking.