Europe Size 56-57 to US: 2XL
Cross-market adult earmuffs and headbands apparel conversion mapping 56-57 specifications into 2XL.

Analyzing Size Equivalence Across Markets
Europe Size 56-57: Corresponds to a head circumference baseline of 57 (22.4 ) with a Standard / Regular fit type.
US: 2XL: Corresponds to a head circumference baseline of 63.5 (25 ) with a Relaxed / Expanded fit type.