When being ironed, some fabrics require more heat and some require less. That's not a problem. TempOK is an indicator that reliably tells you when the desired temperature has been reached. The display will flash while the appliance is still heating up or cooling down, until it reaches the choosen temperature. Although you can still iron, you have not yet attained the right temperature level. As soon as the selected temperature setting is reached, the display will light up continuously.