The LR50 or 1APX is a mercury-free replacement for the once popular Mercuric Oxide MR50 (or PX1) cell that was commonly used in cameras and carriage clocks. Mercury cells are now banned because of toxicity and environmental fears..The LR50 or PC1A cells produce 1.5 Volts, which is higher than the 1.35V produced by the original mercury cell. Most devices accommodate the small increase in voltage and function perfectly..