METAGLAS® – Threaded Sightglass – NPT-Thread

| d2 Thread | SW | d1 | d4 | l | l1 |
| ¼“ NPT | 21 | 9 | 9 | 17 | 11 |
| 3/8“ NPT | 24 | 10 | 12 | 20 | 13 |
| ½“ NPT | 27 | 14 | 16 | 25 | 15 |
| ¾“ NPT | 36 | 18 | 20 | 26 | 16 |
| 1“ NPT | 41 | 21 | 23 | 34 | 19 |
| 1 ¼“ NPT | 50 | 25 | 30 | 30 | 20 |
| 1 ½“ NPT | 55 | 30 | 36 | 36 | 24 |
| 2“ NPT | 70 | 35 | 44 | 40 | 25 |
| 3“ NPT | 100 | 50 | 60 | 55 | 30 |
| Ring materials | Operating temperature |
| Carbon steel 1.0570 | -10°C to +300°C |
| Duplex stainless steel 1.4462 | -30°C to +280°C |
| Hastelloy C22 (2.4602) | -60°C to +300°C |