1) Heat a pot of water to 80-90C (do not boil, this will melt the tray 2) Holding the handle, immerse the nozzle tray in water for about 5-10 seconds. Be careful, because overexposure will melt/shrink the tray, but underexposure will make formation difficult. 3) Remove the tray from the water and hold it to drain the excess water for one second. 4) When the tray becomes soft, put the tray in your mouth and shape it around your teeth. Use your fingers to firmly press the inside and outside of the teeth. Keep the tray firmly in your mouth at the same time. 5) Remove the tray. Repeat this process for the lower tray. Cut off the handle and trim the formed tray, cutting at the gum line. This will allow you to clean any gel that may have leaked onto your gums. 6) Just apply tooth whitening or remineralizing gel and put on the dental tray Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Sold by-YJL official store