Positive Temperature Coefficient(PTC) heating elements are small ceramic stones with self-limiting temperature characteristics. PTC stones have fast heating response times and plateau once the presefined reference temperatures is reached. It gives even heat distribution and quick temperature recovery time.About Ionic Technology:The built-in ionic generator emits negative ions-negative charged atoms and molecules that can interact with the molecular particles in your hair.They seal the hair cuticle reducing frizziness, splits ends, knotting and increasing hair manageability, leaving hair silky and lustrous!Five-Grade Temperature Setting:The operating temperature is 150?(300?),you can short press the temperature button to adjust the operation temperature. Once the temperature is set, then temperature LED setting light will start flashing. It will stop flashing and stay on when the set temperature is reached.