To help you with the conversion of European sizes here is a comparison matrix.  

Let us know if you have any questions!

Mouthpiece Widths

MillimetersUS Size Inches
1104 ¼
1154 ½
1204 ¾
1255
1305
1355 ¼
1405 ½
1455 ¾

Mouthpiece Diameters

MillimetersInches
141/2″
165/8″
183/4″
217/8″
231″