For measuring the inside diameter of pipes, fittings, etc. These calipers are made of hardened steel with points of tempered steel to prevent wear.
| Code | Size mm | Code | Size mm |
| 650151 | 100 | 650157 | 350 |
| 650152 | 125 | 650158 | 400 |
| 650153 | 150 | 650159 | 450 |
| 650154 | 200 | 650160 | 600 |
| 650155 | 250 | 650161 | 750 |
| 650156 | 300 | 650162 | 1000 |