All natural rubber is sensitive to sunlight. The lighter colored bands are the same as the darker colored ones (usually) but are FRESHER. They do have a shelf life. I keep my flight box stash in a brown paper bag inside of a zip lock baggy. No sun damage. I get my #64s at an office supply store. But the darker opaque looking ones I leave on the shelf. Only buy the nice lite brown or tan pastel colored ones. I also hide a tupper ware container with a paper bag and some #64s at the field ...cuz I forget to refill my flight box stash sometimes.