According to A30, what must helmets be compliant with?

Helmets must be compliant with ASTM-SEI certification or equivalent standards because this certification ensures that the helmets have met rigorous safety testing requirements that protect riders' heads from potential injuries during equestrian activities. ASTM International (formerly known as the American Society for Testing and Materials) develops and publishes technical standards for materials, products, systems, and services, ensuring the highest level of safety and performance. The SEI (Safety Equipment Institute) provides a third-party certification, verifying that the helmets comply with these established safety standards.

Choosing this answer reflects an understanding that the safety of equestrian participants should rely on recognized safety certifications rather than unverified or less standardized criteria. While local manufacturing standards or specific brand requirements might provide some level of assurance, they do not guarantee the same level of safety as the ASTM-SEI certification, which is widely acknowledged in the equestrian community for its comprehensive safety testing.