US: M to Europe Size 52-53
Cross-market adult earmuffs and headbands apparel conversion mapping M specifications into 52-53.

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 52-53: Corresponds to a head circumference baseline of 53 (20.9 ) with a Snug / Compact fit type.