Type: Silver Oxide Voltage: 6V. Diameter: 13mm Height: 25mm Also known as: 4SR44, V28PX, PX28, 544, KS28, RPX28, S1325S, S1325, PX28-S, 1406SOP, RFA1611, RFA-16-11.This 4SR4 or PX28-S battery is a popular silver oxide battery. Commonly used in cameras (such as the Minox 35ML, Bronica GS-1 and Canon AE-1), lightweight meters and blood sugar testers. This 4SR44 or PX28-S battery is a popular replacement for the now discontinued PX28 Mercury battery. These mercury batteries, no longer manufactured due to their toxicity, were variously known as PX28, 4MR44, V4034PX, 4H-C, 4NR44, HM-4C. 4SR44 or PX28S batteries have a lifespan of over 8 years, so why not buy two or more? This 4SR44 silver oxide cell has exactly the same dimensions as the alkaline LR44s, but has a longer battery life. You can always use this 4SR44 silver oxide battery instead of a 4LR44 alkaline for improved performance and less frequent battery changes.