Europe Size 54-55 to US: 2XL
Cross-market adult earmuffs and headbands apparel conversion mapping 54-55 specifications into 2XL.

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: 2XL: Corresponds to a head circumference baseline of 63.5 (25 ) with a Relaxed / Expanded fit type.