The brush that straightens your hair Simply brush to smooth and straighten Heats up to 450 degrees. To activate your brush, hold down the Power Button for about 2 seconds until the numbers appear on the display. Then press the +/- buttons until you’ve reached your desired temperature. Hold down the start button for 3 seconds until display illuminates in order to turn on. Brush your hair with the Simply Straight for perfectly straight hair in minutes.