Issued Patents All Time
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 5924249 | Stairway step assembly | William P. Kroll, Karl J. F. Kroll | 1999-07-20 |
| 5664379 | Stairway step assembly | William P. Kroll, Karl J. F. Kroll | 1997-09-09 |
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 5924249 | Stairway step assembly | William P. Kroll, Karl J. F. Kroll | 1999-07-20 |
| 5664379 | Stairway step assembly | William P. Kroll, Karl J. F. Kroll | 1997-09-09 |