Superior Energizer 387S SR936SW Micro Silver Oxide
Dimensions: 11.6mm Diameter x 3.6mm Height
Superior Energizer Micro Silver Oxide SR936SW One Battery Official 387S
Do not use (inherently low performing) alkaline batteries in place of silver oxide in any timepiece.
Made in USA
1.55 volts 60 mAh
This is a primary non rechargeable disposable battery
The 387S is a long life silver oxide chemistry with non-declining power output; alkaline batteries of the same 1.5 voltage start at 1.5 and at the half life are at .8 volts, silver oxide start at 1.55 volts and maintain the voltage until expiring. This is why silver oxide batteries are always used in watches, insulin pumps and sniper scopes or mission critical situations. Never use alkaline batteries for any device requiring a steady constant voltage. A watch with declining voltage cannot give the correct time.
Fits and Replaces:
This is from the American Watchmakers-Clockmakers Institute 2008 Edition Handbook "Battery Number System". This Battery is cross-referenced as: AWCI S78, Energizer 387S, Eveready 387S, Maxell SR936SW, Renata 343, Renata 387S, UCAR 387S, Union Carbide 387S