Made of food-grade silicone, safe, non-toxic and side effects. Good thermoplasticity. Soak in hot water at 75-90C for about 15-20 seconds, it will be very soft at this time, so the soaking time should not be too long, then put the tray into your mouth, press the adhesive surface of the tray and the gum, and shape it to fit you perfectly mouth. If the tray shape is not well done, you can repeat the process for the second mold. Due to inaccurate water temperature and soaking time, the molding effect of the mouthguard is often not good. Even if this product is not molded, it can be remolded in hot water at 75-90C. Use with Whitening Gel (not included). Spread the gel evenly inside the tray so that it touches the outer tooth surface. The appropriate amount of whitening gel is 0.5-1mm thick. (Dry the inside of the denture base with a soft paper before applying the gel so the coating spreads evenly.) Please wash the tray with water before use. The pallet replacement time is 3-4 months. (Note: Mouthguards also help relieve teeth grinding, gnashing, and bruxism for a good night's sleep )