Please be aware that ring sizes shown on musson.com reflect Australian/UK standard sizing. For example, a ring size 6 in the U.S. would be size M in Australian sizing. You can use the International Ring Size Chart to convert your size accordingly.
All other sizing listed on musson.com.au, i.e. length of chain, width, etc. utilise the metric system of measurement and are generally in centimetres (cm) or millimetres (mm).