US: M to Europe Size 62-64
Cross-market adult earmuffs and headbands apparel conversion mapping M specifications into 62-64.

Analyzing Size Equivalence Across Markets
US: M: Corresponds to a head circumference baseline of 57 (22.4 ) with a Standard / Regular fit type.
Europe Size 62-64: Corresponds to a head circumference baseline of 63.5 (25 ) with a Relaxed / Expanded fit type.