There are regular specialty batteries, and then there are Energizer Specialty Batteries. So get the durable, reliable power that keeps going with this Energizer 357/303 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.