Do you have a pair of Gatorz sunglasses in which the rubber ear pieces came off?
Do you have a pair of OutLaw Eyewear sunglasses in which the rubber ear pieces wore out?
Do you just need rubber behind your hears for comfort or to increase the friction holding the sunglasses to your head?
These rubber ear pieces are the answer. Just warm them up in some hot water, then slide them on just like the other kind of "rubber".