The SR54 (V390) button cell battery from Varta is a silver oxide battery of 1.55V. This battery is often used in watches or photo cameras. Because the battery delivers small amounts of power, the battery has a long life.
The SR57 (V399) button cell battery from Varta is a silver oxide battery of 1.55V. This battery is often used in watches, still cameras or other small electronic devices. The battery has a long life.