One Industries Helmets Size Chart

One Industries Gamma Positron Helmet
Adult Helmets
Size Centimeter Inches Hat Size
X-Small 53 - 54 cm 20 7/8 - 21 1/4 6 5/8 - 6 3/4
Small 56 - 56 cm 21 3/8 - 22 6 3/4 - 7
Medium 57 - 58 cm 22 1/8 - 22 7/8 7 - 7 1/4
Large 59 - 60 cm 23 1/8 - 23 7/8 7 1/4 - 7 1/2
X-Large 61 - 62 cm 24 - 24 1/2 7 1/2 - 7 3/4
2X-Large 63 - 64 cm 24 5/8 - 25 128 7 3/4 - 8

Sizing information is provided by the manufacturer and does not guarantee a perfect fit. Please use this chart as a guide only.