I'm your dodo.
HOW TO CHOOSE YOUR SIZE
Find a ring, possibly a “band” type, that is exactly your size.
Use a ruler to measure the inside diameter of the ring and find the equivalent diameter of the circles: for example, if your ring has an inside diameter of 16.56 mm, that corresponds to size 52. If the diameter falls between two sizes, choose the larger size.
For further confirmation:
- Print the two size sheets and use a ruler to check the “20 mm” scale at the bottom right: if the printed measurement is not correct (e.g. if you measure 19 mm with the ruler), DO NOT use it; try to make a printout with the correct scaling.
- Now choose your size by resting the ring on the sheet: the inside diameter of the ring must match the diameter of one of the circles.