The Philips FRx SMART Pads II are single use pads that have a shelf life of 24 months from date of manufacture. All AED pads must be tracked by a management program to make sure that the pads are replaced close to expiration date. Pads are manufactured with a gel adhesion that enables the pad to adhere to the bare skin. Over a period of time, the chemical in the gel breaks down and the efficacy and performance of the pad is not guaranteed. It is important that your AED program track both pad and battery expirations to ensure that your AED is always fully rescue-ready.