Douglas A. Callison

📍 Des Moines, IA: #114 of 657 inventorsTop 20%

🗺 Iowa: #3,091 of 15,303 inventorsTop 25%

Overall (All Time): #1,057,311 of 4,157,543Top 30%

Patents All Time

Issued Patents All Time

Showing 1–5 of 5 patents

Patent #	Title	Co-Inventors	Date
5283994	Landscape timber system	—	1994-02-08
5085404	Staple removing device	Douglas L. Thieleke	1992-02-04
4774823	Trailer hitch lock	—	1988-10-04
4662397	Scheduled fluid control valve	—	1987-05-05
4632361	Scheduled fluid control valve	—	1986-12-30