Size Charts for OSBE Helmets
Adult
| US Size | Centimeters | Inches |
| X-Small | 53 - 54 | 20.87 - 21.26 |
| Small | 55 - 56 | 21.65 - 22.05 |
| Medium | 57 - 58 | 22.44 - 22.83 |
| Large | 59 - 60 | 23.23 - 23.62 |
| X-Large | 60 - 61 | 24.02 - 24.41 |
| XX-Large | 61 - 62 | 24.80 - 25.20 |
Adult
| US Size | Centimeters | Inches |
| X-Small | 53 - 54 | 20.87 - 21.26 |
| Small | 55 - 56 | 21.65 - 22.05 |
| Medium | 57 - 58 | 22.44 - 22.83 |
| Large | 59 - 60 | 23.23 - 23.62 |
| X-Large | 60 - 61 | 24.02 - 24.41 |
| XX-Large | 61 - 62 | 24.80 - 25.20 |