A flat iron, also called a straightening iron, has flat ceramic or metal heated plates and is designed to smooth and straighten hair. To use, place 1" to 2" sections of hair between the iron's heated plates and press firmly, then run the iron down the hair to the ends. Some irons have multiple temperature settings. Use lower heat settings for fine, thin or damaged hair; use higher settings for thick, straight or coarse hair. Ionic-ceramic technology is less damaging to hair and permits irons to heat quickly, evenly and to reach temperatures of over 400°F for fast results.