The 3500 hairdryer diffuser is an attachment that softens the airflow from your dryer allowing you to dry the hair while maintaining its style and shape. The Parlux 3500 diffuser will only fit a Parlux 3500 or Turbo Power Twin Turbo 3500 dryer. The 3500 diffuser is designed to click on to the end of your 3500 model dryer. It is recommended that you use the diffuser at low temperature and speed settings.