Issued Patents All Time
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 5223819 | Material level indicating apparatus with status light and external test features | Norman F. Marsh | 1993-06-29 |
| 5088325 | System for indicating a condition of material | Scott Hewelt | 1992-02-18 |
| 4676100 | Capacitance-type material level indicator | — | 1987-06-30 |