The light that's over the screen is just a regular bulb that I place over a piece of slate in the enclosure to create a basking area. They really never hang out there except for the few times that they come out during the cool part of the year, which is very sparingly.
The UVB in the enclosure comes from the other bulb, which is a Mercury Vapor. I love that bulb because I mist them down every morning and watch them drink, but by night time the enclosure dries out completely, so they're not burrowing in mud.