Use guide 1.It comes flat, drop it in hot water (70 °C) for 10-15 seconds. 2.Take out with tweezers.3.Put the guard in the mouth and gently bite on the middle line of the guard by the upper and lower teeth. At the same time, the tongue is tightened from the inside and molding with your fingers.4.Take out when not in use, drop it in hot water (70 °C) for 10-15 seconds. It can be restored in flat.