Granted Patent
Utility
US 5,592,937 · App. 08/485,172
Respirator mask with stiffening elements
Inventor:
Paul X. Freund
Patented Case
View Patent ↗
Granted: Jan 14, 1997
Filed: Jun 7, 1995
Inventor
Paul X. Freund
Assignee (at issue)
Mine Safety Appliances Company, LLC
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.