It is very strong, be careful when using, Start on the 1 setting, when you point to the tattoo or whatever you are aiming at you will feel the burn or sting. I keep a little water bottle after I laser a bunch of spots I spray to cool it down. So far since I'm only hitting tattoos for a split second a couple of times a day it is lightening them. I have a spot on my throat for years that I used it on and it darkened it but I see a part of it has come off to reveal my regular color skin under so it definetely works but I am going to slow with the process on purpose