Size# 1 Refill: Includes a single Size #1 mouthpiece; For new customers, we recommend you get our 2-Size Starter Kit to determine which size is right for you; Switch to Size #2 only if Size #1 doesn't stop your snoring Ideal For: Those with an overbite (lower front teeth sit behind the upper front teeth) or normal bite with light to moderate snoring; Universal fit, suitable for both men and women Snoring Relief: Targets the root cause of snoring by slightly advancing your lower jaw (+2mm) to keep your airways open while you sleep; Provides immediate snoring relief and all-night comfort so you and your partner can enjoy restful sleep Soft & Comfortable: Lightweight and flexible profile for maximum wearing comfort; Living hinge technology with an open front design enables you to move your jaw freely, breathe naturally and even take a drink of water Convenient: Ready to use out of the box - no boiling or molding needed; Dentist designed, FDA-cleared and approved for OTC use; Made in the USA with BPA and latex-free medical grade material