Did you know that taller cages, screen cages, and tank covers can reduce the amount of UVB rays getting to your reptile? The solution is here: The Reptisun 10.0. This fluorescent bulb features more UVB output than any other lamp. Effective at distance up to 20", compared to 12" with the 5.0 UVB. This lamp will provide the UVA & UVB your pet needs in any cage-situation for up to a full year before needing replacement. Give your reptile the healthy UVA & UVB it needs with the Reptisun 10.0. Size: This is an 18" T-8 (1" diameter) lamp.