Issued Patents All Time
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 6942061 | Muffler for internal combustion engine | David A. Butterfield | 2005-09-13 |
| D492634 | Bidirectional muffler | David A. Butterfield | 2004-07-06 |
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 6942061 | Muffler for internal combustion engine | David A. Butterfield | 2005-09-13 |
| D492634 | Bidirectional muffler | David A. Butterfield | 2004-07-06 |