This technique uses circular needles.
The needle of the circular needle is round, which can better adapt to the curved shape of the scalp and better embed the hair into it. The needles of round needles are softer and can better control the strength and depth to avoid damaging the scalp. The flat needle has a flat needle, which is more suitable for embroidering straight or square patterns on fabric, but is not suitable for tattooing hair seams on the scalp.