This vintage, 1950s, paint can opener was created by the F.B. Williams Co. out of Chicago, ILL. On one side is an advertisement for O'Brien Paints - "Be sure the paint you're buyin' is O'Brien". On the back the device is stamped with Pat. Pending, FB Williams Co Chicago Ill.
I did a little researching and found out the Williams Co applied for a patent for this paint opener in the mid fifties.
The paint opener has been well used and is covered with a patina of paint splatters.