Vintage Double Hose

What year(s) was the Hope-Page mouthpiece produced, first appearance in catalogs, etc...

Working on a research project.

Thanks

M

M
Alec Peirce did a uTube video on the Hope-Page and in it he refers to a classic diving book, which I have or had, not to be found this AM. However I did find in a 1957 Divemaster catalog of an early Hope-Page that was asymmetrical in shape, i.e., one of the intake or exhaust sections was larger. Check out his video and I am sure you will get more answers than I have provided.
Allan

Thanks Allan, will do!

I should have realized thst when all else fails ask Alec!

https://www.youtube.com/watch?v=69eDE2NyvsM

This one shows that asymmetrical H-P mouthpiece. And a cool DivAir!