This module uses DS1307 Real Time Clock. The DS1307 serial real time
clock (RTC) is a low power, full binary coded decimal (BCD)
clock/calendar plus 56 bytes of NV SRAM. Address and data are
transferred serially using I2C, bidirection bus. The clock/calendar
provides seconds, minutes, hours, day, date, month, and year
information.
Size:2.9x 2.6 cm (1.14x 1.02inch)
Battery not included