Issued Patents All Time
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 10989514 | Elastomeric sleeve for tape measure | — | 2021-04-27 |
| 4856554 | Vacuum check valve and method of control | Donald L. Heffner, Dennis G. Merical | 1989-08-15 |
| 4724867 | Vacuum check valve | William H. Gillespie, III, Donald L. Heffner, Dennis G. Merical, James W. Miller, Donald L. Parker | 1988-02-16 |