There are regular specialty batteries, and then there are Energizer specialty batteries. Choose the durable Energizer 337 silver oxide button cell for reliable performance. This battery provides long-lasting energy for all your button cell devices, from household electronics like keyless entry systems to e-book readers, toys, calculators, and watches, as well as heart rate and blood sugar monitors. The mercury-free button cells are also ready to use even after being stored for up to 5 years. Choose Energizer specialty batteries for long-lasting energy you can count on.