Most tippets I've used have an expiration date on them but I've found that these dates are only a recommendation. I think the manufacturers give themselves a good margin of safety. If you take care of them by keeping them out of sun and away from the heat they will last a lot longer. You don't want to keep them on the back shelf of your car, the dash, or in the trunk. I've got some that are four years and more beyond the expiration date and they are fine. If you are in doubt just check them out, and if they don't seem up to snuff replace them.