Headgear Size Head Measurements*
Small 20.5" - 21.6"
Medium 21.6" - 22.8"
Large 22.8" - 24"
X-Large Over 24"

*Measurement is in inches. Measure circumference around head over the forehead area.

demo of how to measure for head gearTo measure: Take a tape measure and measure from the front of the forehead around to the back of the head 2.5" above the ears.