Get the durable, reliable power that keeps going with this Energizer® 377 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. 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.