How to Change the Watch Battery in a Snap Back Watch Case
If you are replacing a National GR927 battery in a Casio calculator please note that your calculator handbook is likely to say that
this is a lithium battery. The handbook is wrong! The replacement for the National GR927 is the 399 silver oxide battery and not
the CR927 3V lithium battery. This mistake in the handbook appears across several different models of Casio solar calculators.
Note: CR/BR (Lithium) battery types are 3.0 Volts.