Bulb manufacturers give us sometimes confusing or misleading information. I have broken down some current bulb packaging labels to see what we can actually learn about their products.
Based on my informal survey, Exo-Terra does an excellent job of showing us consumers the right types of information that should help us make the best choice for our pet and set up. They put actual UVB levels in uW/cm2, and then even calculate how much vitamin D3 can be made by your reptile based on the proportion of the optimal D3 producing UVB rays their bulb produces (not all UV makes D3, in fact UVB at 315 to 330 can destroy D3! ) Exo-Terra packages have easy to understand charts with actual numbers showing distance and temperature for the incandescent and basking bulbs, rather than just graphs you have to interpret. Hopefully we can convince the other manufacturers to do the same, so we can make informed choices.