| Name | Keuffel & Esser 68 - 1955 Deci-Lon Projection Slide Rule |
| Front Scales | Ln-3 Ln-2 Ln-1 Ln-0 A = B T SRT S C = D DI K |
| Back Scales | Sq1 Sq2 DF = CF CIF L CI C = D Ln0 Ln1 Ln2 Ln3 |
| Type of Rule | |
| Material | "clear ""eye-ease"" green unbreakable plastic, with red and black numbers" |
| Dimension (mm) | |
| Area of Use | |
| Origin of Rule | Michael O'Leary |
| Match Number | 4472 |
| Comment | |
| Thumbnail | No Picture |