Simpson's, lightest and most aerodynamic helmet, the SD1 is a premium helmet at a reasonable price. The helmet is tailored towards open wheel dirt track racing with no front vents and a front chin spoiler. NOTE: This helmet is Snell SA2020-certified and is broadly accepted by race organizing bodies and tracks through 2030. Always verify safety rules with your sanctioning body. The Snell Foundation recommends replacement after five (5) years from the date of manufacture. After this period, the helmet’s protective performance may diminish, and it may no longer meet safety requirements or be accepted for use in sanctioned events or competitions.