To obtain Snell approval, manufacturers must first have their helmet DOT approved, only then can they pay to have their helmet tested by Snell. Helmets subjected to Snell testing are put through much more intense procedures than those that just pass the DOT testing standards.

To obtain SNELL approval, once manufacturers have a DOT-approved helmet, they can pay to have their helmet sent to Snell for further testing. SNELL approval is much harder to obtain and helmets go through much more rigorous testing. All motorcycle helmets used for racing have SNELL approval.

Certification under Snell Memorial Foundation standards is voluntary. The standards are more rigorous than the DOT FMVSS 218 standards, which are mandatory for helmets sold for road-going use in the United States. Snell certification indicates that the manufacturer is willing to invest in product quality that rises above the minimum.