My vet recommends 10.0 for Panthers because they live high in the trees and get strong UV unlike other chams that live among the bushes and branches. My Panthers love them. I have measured the UV with my meter and I get 60-80+ from a new bulb whereas from a 5.0 I only get 40-50. When I take the meter outside I can get 180 no problem. That is why the chams like to be outside. I only put my babies under the lower UV bulbs.