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.
new
Gloss Finish
Free US Shipping
We offer Free Shipping on all orders over $99 within the US.
Easy Returns
We have a very easy 30-day Return Policy! Please submit a Customer Support Ticket to get a return Authorization so we can process your return or exchange.
Warranty
We stand behind our products - the 509 industry leading warranty covers every product we make in a variety of ways.
100% Secure Checkout
At 509 we use the best SSL certificate and the most trusted payment processors provided by Shopify Payments so you will be able to buy safely and securely.
With hand-laid carbon fiber construction and a plush interior, the 509 Mach III Carbon Helmet is ready for daily commutes, long hours in the saddle, or weekends spent exploring the windiest highways. Streamlined and built for high-speed riding, this DOT and ECE 22.05 certified helmet includes a shield lock seal, an easy gloves-on access Fidlock® chinstrap, and multiple shield options so you can show your style.
Key Features
- Lightweight, durable hand-laid carbon fiber construction
- Shield lock seal
- Fidlock® chinstrap
- Comfortable plush interior
- Multiple shield options (mirrored and tinted options) → Shop Shields
- DOT and ECE 22.05 certified - global standard (EU and CA)
- WARNING for California residents
Specs
- Starting Weight: 1300g

More than a lifestyle
When you’re riding, you’re part of something much bigger—you’re part of a community driven by a mutual understanding and shared passion for adventure.
We've got you covered.
Explore our street gear.
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.
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 |