The rock is on is under the basking lamp, not the UVB. The UVB is to the side of it. If he sits on that side of the rock, it’s probably 6 inches from the light. It’s 12 inches to the floor. We are in the process of getting him into the 120 gallon zen habitat but they are back ordered until end of May so needed to figure out this lighting ASAP. I had to remove decor as he grew so big. He used to love the tree but lately has loved the hammock on the cool side.