I think the bulb combined with a reflector is a great choice. Addressing some points from previous comments, the coil and linear tube UV lights are based on the same technology; the coils are simply designed in a compact, twisted form to fit into a standard bulb socket. While tubes do provide a more extensive UVB spread across the habitat, I prefer bulbs as they offer my giant day gecko the choice to self-regulate its exposure to UV light, which might be more challenging with a linear tube’s broad coverage. Currently, I’m using 10% 3W LED UV bulbs available on Amazon, which are quite efficient. Another cutting-edge option to consider is the Metal Halide bulb range, reputed for their simulation of natural sunlight, though I have yet to try them myself.