| ELEMENT LEFT SURFACE RADIUS | 1.488 INCHES |
| ELEMENT RIGHT SURFACE RADIUS | 1.366 INCHES |
| ABBE CONSTANT | 55.500 AND 33.800 |
| AXIAL THICKNESS | 0.484 INCHES NOMINAL AND 0.092 INCHES NOMINAL |
| BACK FOCAL LENGTH | 3.169 INCHES |
| COMPOUND LENS EDGE THICKNESS | 0.436 INCHES NOMINAL |
| COMPOUND LENS OVERALL AXIAL THICKNESS | 0.576 INCHES NOMINAL |
| COMPOUND LENS STYLE | DOUBLET |
| DIAMETER | 1.575 INCHES NOMINAL |
| EQUIVALENT FOCAL LENGTH | 3.729 INCHES |
| FSC APPLICATION DATA | SIGHT PERISCOPE M28,INTEGRATED WITH FIRE CONTROL EQUIPMENT |
| INDIVIDUAL LENS STYLE | DOUBLE CONVEX AND DOUBLE CONCAVE |
| MATERIAL DOCUMENT AND CLASSIFICATION | MIL-G-174, CLASS 1, GRADE C MIL SPEC SINGLE MATERIAL RESPONSE |
| MATERIAL | GLASS OPTICAL |
| REFRACTION INDEX | 1.6380 NOMINAL AND 1.6490 NOMINAL |