Hair transplant surgery is an out-patient procedure involving moving healthy hair follicles from the sides and back of the head to balding areas. Because of a principle called "donor dominance", this hair is resitant to DHT and is permanent, making surgical hair restoration an attractive and popular cosmetic procedure for men and women with hair loss. However, cosmetic hair surgery does nothing to stop the progression of genetic pattern baldness. As a result, non-surgical treatments are said to "complement" hair restoration surgery since they may slow down, stop or even reverse the effects of male or female pattern baldness.