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Key Features
Lightweight
Lightweight, carbon fiber construction with our lightest style offered at 1300g
Shuttered Venting
Adjustable shuttered venting at key areas of helmet shell
Shield Lock
Shield lock and eye port gasket for air-tight seal eliminating wind noise
Aerodynamic
Aerodynamic design with durable ABS construction
Fidlock® Magnetic Chin Strap
Comes standard with Fidlock® easy-open magnetic strap clasp
Drag
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
- ITO (Indium Tin Oxide) shield coating to prevent surface scratches and fogging
- Fidlock® The Fidlock System is a cutting-edge magnetic chinstrap buckle used in motorsport helmets ensuring quick, secure, closures with one hand and is DOT and ECE compliant.chinstrap strap closure for easy in and out
- Comfortable plush interior
- Multiple shield options (mirrored and tinted options)
- Universal camera mount capable
- WARNING for California residents
Specs
- Helmet Certification: DOT & ECE 22.05
- Starting Weight: 1300 grams
- Best Head Shape: Intermediate oval fit
- Size Range: XS - 2X
- Shell Breaks:
Small shell - XS, SM, MD, LG
Large Shell - XL, 2X - Included items: 509 helmet drawstring bag, breathbox, 509 Sticker
Size Guide
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.
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 below.
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.
