CR1620 button batteries are high energy non-rechargeable Lithium cells. The CR1620 size provides extended life for common applications such as car key fobs, remote controls, watches, organisers and calculators, as well as a wide range of other electronic equipment. We supply CR1620 in packs of 2, but they have an extremely long shelf life, losing less than 1% of their charge a year so why not take a couple extra as spares.