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 (and2mm) 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 and 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