Step 5 works more efficiently with a Lip Seal Device worn at nights
What size do I need?
Measure around your head, from under your chin to the crown of your head going just in front of your ears (above your forehead), and back to the starting point under your chin.
Median Sizes are:
Small fits where the measurement is around 54cm
Medium fits where the measurement is around 60cm
Large fits where the measurement is around 66cm