The key to a good hair transplant is naturalness of the first lines in the hairline. To obtain this, several criteria must be followed. In order to imitate nature, the first 4 to 5 front lines must be created hair by hair and the density should only be increased beginning at the 5th or 6th line, at which point follicular units of 2 hairs each are inserted, creating a density effect in degradé. Further, the hairline cannot be created with a straight line, but must be irregular. Finally, we separate out the finest of the single hair FUs, called ultrafines, and place them before the first lines to achieve a feathery aspect found in nature.