You will get the most protection from a helmet if it is all of the following, except:

A helmet will provide a rider with the best protection if it meets U.S. Department of Transportation (DOT) standards; fits snugly all the way around; and has no obvious defects, such as cracks, loose padding, or frayed straps.

U.S. DOT-compliant.
Loose-fitting.
Free of defects.

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