First, adjust the grill mouthpiece to the shape of the mouth. Then, insert the silicone fixing bar in between the back prongs of the grillz and place both in hot water together. Once the bar softens and becomes clear, remove the mouthpiece from the water and place it onto your teeth. Adjust as necessary for the fit and look you desire. The fixing bar should take approximately 15-20 seconds to harden. Now you have grillz that fit your teeth perfectly!