Use this size chart to determine your correct fit in the Fox Proframe RS full face helmet.
| Size | Head Circumference |
| S | 51-55cm |
| M | 55-59cm |
| L | 59-63cm |
How to measure your head size:
Measure your head circumference in centimeters by wrapping a flexible tape measure around the largest portion of your head—about one inch above your eyebrows.
Tip: If you don’t have a flexible tape measure you can also use a piece of string and then measure the length of the string after with a ruler.