This is the DS1307 Real Time Clock developed by one of our designer waiman. The module comes fully assembled The DS1307 is accessed via the I2C protocol. Two wire I2C interface. Hour:Minutes : Seconds AM/PM. Day Month, Date - Year. DS1307 based RTC without LIR2032 battery 1Hz output pin. 56 Bytes of Non-volatile memory available to user. Size:2.9cm x 2.6cm - 1.14inch x 1.02inch.