Granted Patent
Utility
US 6,055,983 · App. 08/998,921
Respirator filtration device
Inventor:
Karl Metzger
Patented Case
View Patent ↗
Granted: May 2, 2000
Filed: Dec 29, 1997
Inventor
Karl Metzger
Assignee (at issue)
Parmelee Industries
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.