-----
Hello Chris,
Centrix was a french brand created by the firm Gentil et Cie in 1923 which produced stems and bars of both steel and alloy.
The company ceased play in 1962.
At times in its history it worked with MAVIC and with Freres Huret. There were Centrix badged derailleurs which were licensed from Huret.
The Schwinn Continental tenspeed of 1960-61 came with a Centrix alloy stem.
Some of their stem models were distinctive for their use of a double binder.
The name can be a source of confusion as it his also seen on bicycles and coaster brakes.
These are unrelated to Centrix brand stem and bar products.
-----