Sonic Electric Toothbrush U Shape Automatic Teeth Whitening Kit with 2 Replacement Heads A single brush head can be used for 6-12 months (this set is also equipped with a replacement brush head). ^The number of bristles increased from 768 in the third generation to 1908. In order to better brush teeth and massage gums, the external test also adds a brush head.^Four modes of one key operation: A. strong mode, strong brushing; B. Medium mode, comfortable brushing; C. The way of gum massage; D. Whitening mode of tooth whitening.This U-shaped toothbrush, you just need to gently bite it, and then swing left and right to clean the toothbrush 360 degrees.^Gently bite the brush head and use the sound wave vibration to clean your teeth in an all-round way. You can make up while brushing your teeth or wear clothes. ^This electric toothbrush will make your morning time more effective. When you use the blue light whitening mode, you can completely free your hands.