What were Conn "hydraulic expansion protexts"?

[Michael Bush]

http://cderksen.home.xs4all.nl/Conn14J1955image.html

Anybody know?

[The Big Ben]

Is this the same process known as "hydroforming"?

[Rane]

I'm not familiar with "protexts." Maybe the text should read "protects" instead of "protexts" as the hydraulic forming presses the brass outward toward the walls of the die instead of drawing the outside edges inward like if it was bent mechanically, thus preserving the desired diameter(s) instead of slightly reducing/changing it.

C and X are right next to each other on the keyboard too.

/wild guess