AG8 L1121 LR1120 LR55 391
Size: 11.6 x 2.05 mm 1.5v Alkaline Manganese
Used in a wide variety of apllications including : Toys, Calculators, Watches, Clocks, Meters, LCD tools, Testers, Thermometers, and all manner of gadgets.
These can be used in place of Silver Oxide Cells in many applications as well, to save money, but bear in mind the voltage drop experienced, towards the end of the battery life, can mean more frequent replacements.
Generally sold in pairs or 10-packs, they are economical to purchase, compared to other types of watch battery.