Europe Size 54-55 to US: M
Cross-market adult earmuffs and headbands apparel conversion mapping 54-55 specifications into M.

Analyzing Size Equivalence Across Markets
Europe Size 54-55: Corresponds to a head circumference baseline of 55 (21.7 ) with a Standard / Regular fit type.
US: M: Corresponds to a head circumference baseline of 57 (22.4 ) with a Standard / Regular fit type.