Granted Patent
Utility
US 4,936,411 · App. 07/234,427
Detectable earplug
Inventor:
David LEONARD
Patented Case
View Patent ↗
Granted: Jun 26, 1990
Filed: Aug 19, 1988
Inventor
David LEONARD
Assignee (at issue)
Cabot Corporation
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.