The DS3231 RTC chip features:
  •  Accurate to within 2 minutes per year
  •  Internal temperature compensated TCXO oscillator
  •  32KHz square wave output
  •  Additional programmable square wave output
  •  24 hour or 12 hour with AM/PM
  •  2 built-in alarms
  •  Automatic number-of-days in the month
  •  Automatic leap years
  •  On-board AT24C32 EEPROM chip (32Kb, 4K Bytes) with adjustable I2C address
  •  100KHz / 400KHz I2C bus communications
  •  Complete with 3V 2032 battery
  •  5V (Nano / Uno / Mega) Arduino compatible
  •  3.3V Pi compatible version available upon request (for the same price)

Please see Maxim Integrated DS3231 datasheet for full specification.

+5V Operation
Every manufacturer's DS3231 ZS-042 modules, when using them with a 5V Arduino, you should disable the "charging" components to protect against damage to the 3V battery

+3.3V Operation
The charging components don't need to be disabled.

Please choose when ordering if you would like the components disabled for +5V use.