Granted Patent
Utility
US 5,920,021 · App. 09/055,839
Drum head with sound attenuating annular coating
Inventor:
John J. Good
Patented Case
View Patent ↗
Granted: Jul 6, 1999
Filed: Apr 6, 1998
Inventor
John J. Good
Assignee (at issue)
Drum Workshop, Inc.
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.