 the sun basically has something called UV light, right? And it comes essentially in three forms. UVC, which is filtered out by the atmosphere. UVB, which is a very small percentage, which burns the skin. And then UVA, which is actually most of the ultraviolet light. And the sunscreens in the U.S. have a number on them. So if you see like 50 on the front of a sunscreen, that means that the sunscreen has a 50 rating for blocking UVB.