The PCL used in Dermapen 4 is the same as the meltable thread component used in the thread lift for sagging treatment in the field of cosmetology. PCL that has penetrated under the skin has the effect of promoting the production of new collagen, and can be expected to improve the firmness, elasticity, and wrinkles of the skin that have been lost with age. In addition, it is said that it will appear little by little over 1 to 2 weeks after the treatment.