I stumbled upon this little device today, and since it was Bell System, decided it needed a place in my collection.

Any ideas what it was designed to do?

Front
[img]https://www.flickr.com/photos/phone-man/7027719315/[/img]

Back of unit
[img]https://www.flickr.com/photos/phone-man/6881621064/[/img]

The long metal component says "Danger high pressure, do not open 337A WE"

Any Ideas?


Will G.