| Name | Keuffel & Esser <4071 T> Duplex with Trig scales, L scale on back, not on edge, dated 1913 |
| Front Scales | A = B S C = D |
| Back Scales | A = BI T CI = D L |
| Type of Rule | slide rule |
| Material | engine divided celluloid laminated mahogany |
| Dimension (mm) | |
| Area of Use | generic |
| Origin of Rule | Bob Otnes |
| Match Number | 4499 |
| Comment | |
| Thumbnail |  |