| Number | Name | Date | Kind |
|---|---|---|---|
| 24660 | Potts | Jul 1859 | |
| D314820 | Sullivan | Feb 1991 | |
| 567231 | Glauber | Sep 1896 | |
| 925762 | Eager | Jun 1909 | |
| 1908821 | Cornell, Jr. | May 1933 | |
| 2086007 | Tompkins | Jul 1937 | |
| 2215318 | Bristol | Sep 1940 | |
| 3610288 | Carr | Oct 1971 | |
| 3645566 | Dyck | Feb 1972 | |
| 4067353 | DeHoff | Jan 1978 | |
| 4491349 | Rice et al. | Jan 1985 | |
| 4750411 | Eversole | Jun 1988 | |
| 4773197 | Sullivan | Sep 1988 | |
| 5036636 | Hasty | Aug 1991 | |
| 5080403 | Paolyccio | Jan 1992 |
| Number | Date | Country |
|---|---|---|
| 871635 | Jun 1961 | GBX |
| Entry |
|---|
| Exhibit A-Photograph of prior air duct riser. |
| Exhibit B-Photograph of prior air duct riser. |
| Sales information from Northern Pipe Products and GPK Products, Inc. (Undated but believed to be prior art to the present application). |