But sunglass straps are also very convenient in casual situations where you need to take your shades on and off: think, going in and out of stores while shopping or working in the yard. In these cases, you won’t need to find a place for your sunnies every time you take them off. In short, eyewear retainers make sunglasses easier to deal with and less likely to break or get lost (for example, at the bottom of the lake or ocean). http://www.hontaipacking.com/glasess-case/eva-zipper-glasses-case/