You're going to LOVE the fit. Try it on and experience our perfect fit. If you don't love it, send it back in new and unused condition within 30 days for an exchange or full refund*. Risk free.
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We have a very easy 30-day Return Policy! Visit our Return and Exchanges page for more information.
We stand behind our products – with a 3 year warranty against materials and workmanship for all helmets.
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Elevate your game with the next-generation performance of the 509 Altitude 2.0 Offroad Pro Helmet featuring the latest in weight-saving design and breathable comfort. Trail or track, the Altitude’s bestselling package twists the throttle wide open on airflow with a 40% larger chinbar intake and rear exhaust vents to keep you cool no matter what. Top of the line in every way, it includes the Fidlock® magnetic strap buckle for easy one-handed operation, plus MIPS protection for an added layer of security and peace of mind.
Key Features
- Hand lay-up fiberglass composite construction
- Pro MIPS® Brain Protection System for ultimate safety → Learn More
- Fidlock® chinstrap strap closure for easy in and out
- DOT certified
- Upper vents for optimal airflow - Hi-Flow
- Go-Pro® mounting capability → Shop Universal Helmet Camera Mount
- Adjustable visor with Lifetime Warranty
- 3 Shell Design for XS to 2X Sizing
- Perfect fit between helmet eyeport and 509 goggles → Shop All Dirt Bike Goggles
- 509 helmet bag included
- WARNING for California Residents
Specs
- Starting Weight:200 grams
Size Guide
Not sure about your size? Try on at your local dealer!
*Street Helmets are a tighter fit due to cheekpad compression, however, they do pack out over time/use.
How to Measure
When measuring your head, use a cloth tape. Start it just above your eyebrows and circle it around the thickest point in the rear of your head and then reference the size guide above.
Scroll to the right to see more sizes
| Size | US Hat Size | Inches | Centimeters |
| X-Small | 6 5/8 - 6 3/4 | 20 7/8 - 21 1/8 | 53 - 54 |
| Small | 6 7/8 - 7 | 21 5/8 - 21 7/8 | 55 - 56 |
| Medium | 7 1/8 - 7 1/4 | 22 1/2 - 22 5/8 | 57 - 58 |
| Large | 7 3/8 - 7 1/2 | 23 1/4 - 23 1/2 | 59 - 60 |
| X-Large | 7 5/8 - 7 3/4 | 24 - 24 1/4 | 61 - 62 |
| 2X-Large | 8 | 24 3/4 - 25 | 63 - 64 |
| 3X-Large | 8 3/4 | 25 1/4 - 25 3/4 | 64 - 65 |
| 4X-Large | 9 | 26 - 26 1/4 | 66 - 67 |
| Youth Small | 6 | 18 1/8 - 18 7/8 | 47 - 48 |
| Youth Medium | 6 1/8 - 6 1/4 | 19 1/4 - 19 5/8 | 49 - 50 |
| Youth Large | 6 3/8 - 6 1/2 | 20 - 20 1/2 | 51 - 52 |
Pressure Points
When trying on a helmet, take note of any pressure points on your forehead—a sign that the helmet is too round. Pressure points on the sides of your head indicate a helmet is too oval for the shape of your head. After you buy a new helmet, try wearing it for 30 to 45 minutes to check for pressure points before using it on a ride.
Pressure Points
When trying on a helmet, take note of any pressure points on your forehead—a sign that the helmet is too round. Pressure points on the sides of your head indicate a helmet is too oval for the shape of your head. After you buy a new helmet, try wearing it for 30 to 45 minutes to check for pressure points before using it on a ride.