Bought this because I have a couple outbreaks a year and thought I would be ready for the next one. Followed all the instructions and the light would not come on. Replaced the battery not knowing how long it may have been in the unit on a shelf and nothing. The silver tip looked like it had already been in contact with the emery board so I was probably sold a defective unit to begin with. It was a lot of money so I can't imagine they thought no one would notice. Geez.