The greatest part about the I/O goggles is how easy and fast it is to switch lenses. Smith makes a large variety of replacement lenses- and extra lenses don't take up any room. They are so nice to have if the light changes or you forgot to dry out the lenses that are in your goggles from yesterday and they start fogging up. My favorite lenses for low light are the red sensor mirrors, and for super sunny days any of the Sol-X are great. Most goggles come with the Ignitor mirror, which is a medium light/ allaround lens.