- Graduation 0.01mm
- Measure width of grooves inside bores
- Non-rotating spindle
- Two graduations for inside and outside measurement
| Code | Range(Outside) | Range(Inside) | Accuracy |
| 3287-25A | 0-25mm | 1.6-26.5mm | 10μm |
| 3287-50A | 25-50mm | 26.5-51.5mm | 10μm |
| 3287-75A | 50-75mm | 51.5-76.5mm | 10μm |
| 3287-100A | 75-100mm | 76.5-101.5mm | 10μm |