Step 1. Download this image bellow
Step 2. Print the sizer, ensuring that your print settings are set to 100%
Step 3. When printed, measure from A to B to ensure that it is 8.89 cm
Step 4. Slice along the line at A, then fit B into the slot made measuring around your chosen finger. Ensure that you leave room for your knuckle to fit.
If your ring falls between a number, choose the larger one. Please note, this is USA size, please indicate this when requesting your ring size.