US: M to Europe Size 60-61
Cross-market adult earmuffs and headbands apparel conversion mapping M specifications into 60-61.

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 60-61: Corresponds to a head circumference baseline of 61 (24 ) with a Relaxed / Expanded fit type.