When my two rescue kittens started to lose patches of fur I knew that was a sign of ringworm. You can go to the vet and spend hundreds of dollars or you can confirm yourself with a blacklight, which is exactly why I bought this. I checked with the backlight and they lit up which was a sure sign that they had infections, which I was then able to treat at home completely- saving me the hefty vet bill. I would highly recommend this, it does show what it claims to and gets the job done!