The helmet internals degrade over time. this is from the Shoei website. When do you have to replace a helmet with a new one? For safety reasons, we recommend replacing a helmet after about seven years. The outer shell (fiberglass) is relatively resistant against aging. However, the material of the inner shell (EPS), which is substantially involved in the safety (shock absorption), hardens with time. So the inner shell no longer has those important absorption characteristics. There has also been much work on the development of helmets in recent years. Improved helmet shells, advanced materials, better comfort, changeable inner lining, more efficient ventilation systems, higher requirements also in the official test standards such as the E22 homologation, visor quick-change systems, etc. - in summary it can be said that helmets have simply become safer. From the Schuberth website Depending on usage and care, you should replace the helmet every 5-7 years. Although the outer shell is in principle suitable for a longer service life, wear of the other components may affect the overall action of the helmet. For this reason we recommend that you replace the helmet after the period of use stated above for your own safety. Unfortunately there is no way of verifying the protective action of the helmet without destroying it. Because of this, SCHUBERTH does not offer this test.