Size Chart
| Diameter | Indian Standard | US Standard |
| 15.0mm | 7 | 4 |
| 15.03mm | 8 | 4.5 |
| 15.6mm | 9 | 5 |
| 16mm | 10/11 | 5.5 |
| 16.5mm | 12 | 6 |
| 16.8mm | 13 | 6.5 |
| 17.2mm | 14 | 7 |
| 17.6mm | 15/16 | 7.5 |
| 18.2mm | 17 | 8 |
| 18.6mm | 18/19 | 8.5 |
| 19.1mm | 20 | 9 |
| 19.4mm | 21 | 9.5 |
| 19.7mm | 22 | 10 |
| 20mm | 23/24 | 10.5 |
| 20.6mm | 25 | 11 |
| 21.0mm | 26 | 11.5 |
| 21.3mm | 27 | 12 |
