Granted Patent
Utility
US 4,413,372 · App. 06/320,721
Shoe attachment for wet/dry electric vacuum cleaner
Inventor:
Robert C. Berfield
Patented Case
View Patent ↗
Granted: Nov 8, 1983
Filed: Nov 12, 1981
Inventor
Robert C. Berfield
Assignee (at issue)
SHOP VAC 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.