DS1307 I2C real-time clock chip (RTC) 24C32 32K I2C EEPROM memory Battery LIR2032 (not included) Two wire I2C interface Hour : Minutes : Seconds AM/PM Day Month, Date - Year Size: 28x25x10mm Leap year compensation Accurate calendar up to year 2100 1Hz output pin 56 Bytes of Non-volatile memory available to user