Digital Fast Brush Electric Hair Straightener Electric Brush Hair Straightener Comb. Different settings of the straightener can provide you with various temperature settings to obtain straight hair. The straightener is equipped with an add-subtract key which can regulate temperature at “+” and “-” levels, which will increase temperature by 5 degrees Celsius per touch. It’s recommended that you select the highest temperature at first, and then decrease temperature level on the basis of your hair quality