Keeping your glasses safe is the only way you'll extend their life-span. By having them hanging around your neck you're never going to loose them, accidentally step on them or scratch them on a table! These Costa keeper glasses retainers will ensure their safety & prolong the life of your sunglasses. & the cloth on these is super-soft & comfortable so no need to worry about them irritating the back or sides of your neck. Code: Black: F-CK11 Code: Blue: F-CK17