Follicular unit transplantation is a hair restoration technique where a patient's hair is transplanted in naturally occurring groups of 1 to 4 hairs called follicular units. Follicular units also contain sebaceous (oil) glands, nerves, a small muscle and occasional fine vellus hairs. In follicular unit transplantation, these small units allow the surgeon to safely transplant thousands of grafts in a single session which maximizes the cosmetic impact of the procedure.