Our ThermoForm Bleaching trays are made from a clear, see-through polymer. This is important because you want to see your teeth as you are placing your bleaching tray on your teeth. This is necessary so that you can assure that the gel is spreading throughout the tray and providing full coverage on all of your teeth. Many other trays are made from colored plastics or hazy plastics that are difficult to see through. Use of non-clear trays can lead to nonuniform whitening of your teeth.