K2 Black Hawk One Helmet Size Chart
| Size | cm |
| S | 55-56 |
| M | 57-58 |
| L | 59-60 |
| XL | 61-63 |
K2 helmet sizing is determined by the distance around your head in centimeters. Measure the circumference of your head just above your eyebrows to determine your correct helmet size.
