509 Altitude Pro Series Helmet Liner
Replacement liner for 509 Altitude and Altitude Carbon Helmets.
- SM liner provides a tighter fit in size MD helmet
- MD liner provides a looser fit in size SM helmet
- XL liner provides a tighter fit in size 2XL helmet
- 2XL liner provides a looser fit in size XL helmet.
509 Helmet Sizing
Sizing information is provided by the manufacturer and does not guarantee a perfect fit.
How to Measure
- H HEAD
Wrap a cloth measuring tape around your head just above your eyebrows and ears. Pull the tape comfortably snug, read the length, repeat for good measure and use the largest measurement.