United Kingdom Size Comfort Large to US: Small / 51mm

United Kingdom Size Comfort Large: Corresponds to a nominal width of 55 $\text{mm}$ (2.17 $\text{in}$), length of 195 $\text{mm}$ (7.68 $\text{in}$), average structural girth of 110 $\text{mm}$ (4.33 $\text{in}$), and fit category Medium-Large / Comfort.

US: Small / 51mm: Corresponds to a nominal width of 51 $\text{mm}$ (2.01 $\text{in}$), length of 180 $\text{mm}$ (7.09 $\text{in}$), average structural girth of 102 $\text{mm}$ (4.02 $\text{in}$), and fit category Small / Regular-Narrow.