Yes. The helmet must be Snell SA 2010, Snell SA 2015, or an FIA certified Simpson helmet to be relined.
Using a cloth tape measure, measure around the head , beginning right above the brow. Refer to the size chart for conversions in both hat sizing and XS-XL.
Your helmet should fit tightly to your head without being uncomfortable. You helmet should be well seated at the crown and you should feel contact with even pressure around your head. Cheek and ear areas can be custom fitted.
Simpson currently certifies helmets to Snell SA 2015, SFI, FIA 8859 and 8860, CMR, DOT and ECE standards.
Snell recommends that you replace it every five years. Your helmet should be inspected by a professional following any impact. Remember, you only have one head and racing is a dangerous sport. If you are in doubt regarding your helmet’s performance and integrity, get a new one.