DS1302 Real Time Clock Module (Battery included)

Comes with batteries included!

The Real Time Clock (RTC) module allows you to add precise time functionality to your Arduino circuits. Applications include date and time display (clocks), countdown timers, time controlled actuation etc.

NB: It can also be used without the CR2032 battery in place, but with this the time is lost and reset as soon as you disconnect it from the power.