Granted Patent
Utility
US 6,789,989 · App. 10/097,446
Screw having a head with concave underside
Inventor:
Uli Walther
Patented Case
View Patent ↗
Granted: Sep 14, 2004
Filed: Mar 13, 2002
Inventor
Uli Walther
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.