There are regular specialty batteries, and then there are Energizer Specialty Batteries. So get the durable, reliable power that keeps going with this Energizer 389 Silver Oxide Button Cell Battery. It delivers long-lasting power to your button-battery-operated devices, from household electronics like keyless entry systems, to e-books, toys, calculators, and watches, to heart rate and glucose monitors. And these zero-mercury coin batteries can hold power for up to five years in storage. Choose Energizer Specialty Batteries for long-lasting power you can count on when you need it.