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509 Altitude Helmet Size Chart
509 Adult Altitude Helmet Size Chart
| Size |
XS |
SM |
MD |
LG |
XL |
2XL |
3XL |
4XL |
| US Hat Sizes |
6 5⁄8 - 6 3⁄4
|
6 7⁄8 - 7 |
7 1⁄8 - 7 1⁄4
|
7 3⁄8 - 7 1⁄2
|
7 5⁄8 - 7 3⁄4
|
7 7⁄8
|
8 - 8 1⁄8
|
8 1⁄4
|
| Inches |
20 7⁄8 - 21 1⁄4
|
21 5⁄8 - 22 |
22 3⁄8 - 22 3⁄4
|
23 1⁄8 - 23 1⁄2
|
23 7⁄8 - 24 1⁄4
|
24 5⁄8
|
25 - 25 3⁄8
|
25 3⁄4
|
| Centimeters |
53 - 54 |
55 - 56 |
57 - 58 |
59 - 60 |
61 - 62 |
63 |
64 - 65 |
66 |
509 Youth Altitude Helmet Size Chart
| Size |
SM |
MD |
LG |
| US Hat Sizes |
6 |
6 1⁄8 - 6 1⁄4
|
6 3⁄8 - 6 1⁄2
|
| Inches |
18 1⁄8 - 18 7⁄8
|
19 1⁄4 - 19 5⁄8
|
20 - 20 1⁄2
|
| Centimeters |
47 - 48 |
49 - 50 |
51 - 52 |
