Siemens & Halske Thread was used in
telephones approx. 1900 AD.
The flank angle ranges from 50° to 68°
| Thread No. | Major Diameter | Tapping Drill Size | Pitch | Thread Angle |
| mm | mm | mm | ° | |
| 11 | 8.95 | 7.00 | 1.21 | 50 |
| 14 | 7.20 | 5.70 | 1.05 | 58 |
| 17 | 6.00 | 4.60 | 0.89 | 55 |
| 18 | 5.75 | 4.50 | 0.78 | 58 |
| 21 | 5.12 | 4.00 | 0.78 | 58 |
| 25 | 4.00 | 3.18 | 0.66 | 61 |
| 27 | 3.37 | 2.58 | 0.66 | 68 |
| 29 | 2.80 | 2.22 | 0.53 | 66 |
| 31 | 2.16 | 1.63 | 0.49 | 68 |
| 33 | 1.78 | 1.39 | 0.34 | 59 |
| 34 | 1.63 | 1.29 | 0.30 | 55 |
| 36 | 1.22 | 0.95 | 0.22 | 50 |