Derma Roller- is a tool initially made for collagen production in the skin to cure wrinkles, scars, stretch marks and various skin irregularities. Research, later on, found out that when you roll the roller on your head or beard it causes hair and beard growth. How do you ask? Well, The small needles of the beard roller puncture the skin, the body recognizes this damage and begins the healing process by sending keratin and collagen, which are components that makeup hair. So it's sending hair to the areas you use the derma roller over.