| Number | Name | Date | Kind |
|---|---|---|---|
| 4353611 | Siebens et al. | Oct 1982 | |
| 4611093 | Farmer et al. | Sep 1986 | |
| 4782197 | Stunzi et al. | Nov 1988 | |
| 5092798 | Muench | Mar 1992 | |
| 5483023 | Barnes | Jan 1996 | |
| 5548089 | Yamat | Aug 1996 | |
| 5808536 | Sandlin, Jr. et al. | Sep 1998 |
| Entry |
|---|
| "Tuf Well", Product Announcement, Components Operation, Coltec Industries, May 1, 1990, 4 pages. |