Use this guide to determine which size of LadyBuds, GoodSleep or Flier earplugs you should purchase. When you receive your earplugs, return to this page and use the following link: http://www.otifleks.com.au/assets/otifleks-sizing-guide.pdf
to help you measure your finger before opening the box or using the earplugs. That way, you can return the earplugs for a different size if you find you have ordered the wrong ones. Do not measure your finger on your screen!Step 1
Place your little finger into your ear to check how it fits.
If the tip of your little finger is too large for the entrance of your ear canal, you should buy one size smaller than your finger shows on the credit card.
If the tip of your little finger is too small and can enter the ear canal easily, buy one size larger than your finger shows on the credit card.
If the tip of your little finger covers the entrance of your ear canal perfectly, then buy the size that your finger shows on the credit card.Step 2
Place your credit card on a flat surface.
Place your little finger on your credit card.Align your finger to the left of the first number on the card.
Do not align it with the edge of the credit card,
Note: make sure your finger just touches the card. Do not push your finger down.
Then see how many numbers your finger covers.
Small: if your little finger DOES NOT exceed the first 3 numbers
Medium: if your little finger DOES NOT exceed the first 4 numbers
Large: if your little finger DOES NOT reach the 5th number
XL: if your little finger DOES exceed the 5th number.
Et voilà - your ear size is predicted with good accuracy!
More details online here