This starter pack is designed for new customers and comes with 2 differently-sized mouthpieces and a protective storage case. Mouthpiece sizing is based on how much forward movement your jaw needs (not the size of your mouth). Size #1 moves the jaw forward just a little and #2 moves it further. Determine which one stops your snoring and then order a refill of either Size#1 or Size#2 (both sold separately). We recommend replacing your ZQuiet every 4-6 months, for proper hygiene and optimal performance. The ZQuiet Mouthpiece is unique due to its low profile and soft material, making this device less intrusive than similar products with a hard plastic shell. ZQuiet’s living hinge technology with an open front design allows you to breathe easily. Minor side effects, including drooling or sore jaws are normal and should disappear with continued use.