United Kingdom Size Small Comfort to US: Slim / 49mm

United Kingdom Size Small Comfort: 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.

US: Slim / 49mm: Corresponds to a nominal width of 49 $\text{mm}$ (1.93 $\text{in}$), length of 175 $\text{mm}$ (6.89 $\text{in}$), average structural girth of 98 $\text{mm}$ (3.86 $\text{in}$), and fit category Snug / Close.