Granted Patent
Utility
US 4,728,933 · App. 06/843,438
Miniature dual cavity ringer
Inventor:
Frank Mazza
Patented Case
View Patent ↗
Granted: Mar 1, 1988
Filed: Mar 24, 1986
Inventor
Frank Mazza
Assignee (at issue)
US
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.