SR621SW Button Cell

About the SR621SW Battery
SR621SW is the name of a small 1.55 volt battery.  It is a popular battery for watches and other small electronics. 
S stands for its silver-oxide positive electrode terminal.
R stands for its round shape.
6 stands for 6.8 mm diameter.
21 stands for 2.1 mm height.
S stands for its sodium hydroxide electrolyte.
W means the battery meets the International Electrotechnical Commission (IEC) standard for watch batteries.
Capacity: 20 mAh
Voltage: 1.55V

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SR621SW Batteries on Amazon

SR621SW Battery Specifications

NamesSR60, SR621, SR621W, 363
Diameter6.8mm
Height2.1mm
Capacity20 mAh
Voltage1.55 volts
ShapeRound
Electrochemical SystemMetal hydroxide electrolyte. Zinc negative electrode. Silver-oxide positive electrode.

Alkaline Equivalents

NamesAG1, LR60, LR621
Diameter6.8mm
Height2.1mm
Capacity13 mAh
Voltage1.5 volts
ShapeRound
Electrochemical SystemMetal hydroxide electrolyte. Zinc negative electrode. Manganese dioxide positive electrode.

Where to Buy
Brand names such as Energizer and Duracell will have their own names.  They use 164 or 364 for their identical battery names. They can be found in many drug stores and department stores.

How to Save Money

It is possible to substitute the alkaline version of the battery which costs less.  AG1 is the common name of most alkaline versions of the same size battery. The capacity, however, is less. AG1 batteries have a capacity of 13 mAh.

SR920SW