- Used for inspecting the flatness of very flat surfaces.
 158-118 |  |
Specifications:
| Metric | |||
| Order No. | Thinkness (mm) | Diameter (mm) | Flatness grade (µm) |
| 158-117 | 12 | 45 | 0.2 |
| 158-118 | 0.1 | ||
| 158-119 | 15 | 60 | 0.2 |
| 158-120 | 0.1 | ||
| Inch | |||
| Order No. | Thinkness (in) | Diameter (in) | Flatness grade (in) |
| 158-122 | 0.5 | 1.8 | 0.000004 |
| 158-124 | 0.6 | 2.4 | |
