This is a Mini Real-Time Clock module, it design for Raspberry Pi, but it also can be used to Arduino.

Pluging it into Raspberry Pi GPIO interface, and all is ok. This is the easiest way to keep it in time.

Features:

Smaller

Work in 3.3V and 5V

Supported Raspberry Pi and Arduino

Compatible with Raspberry Pi A+,B,B+/2.

Specification:

DS3231 RTC IC

Self-adjust 3.3V and 5V

Size: 14x14x12 mm

Include:

1x RTC Module

1x Battery