The thicker and darker the hair, the bigger the follicle, the deeper the melanin, the more receptive it is to laser action, and the better the effect of destruction. The long pulse laser can also treat red blood cells, using the absorption peak of hemoglobin, which can clot the hemoglobin in blood vessels, and it can also treat acne, such as scars and erythema, because it works on the lymphatic vessels in the skin