There are more types of lasers, which all have light source emitting devices, such as Q1064 laser or 308 laser, and carbon dioxide laser. However, the physical composition and principle of action of mole pen has nothing to do with laser. Mole pens are generally divided into two types, one is similar to a small spray can-like device, which is filled with liquid nitrogen and treats pigmented moles or superficial swellings by freezing. There is another kind of pen-like device, which contains corrosive liquid, such as trichloroacetic acid, which is applied to the pigmented mole to remove it through corrosion. Mole pens are completely different from lasers.