The DS1307 is the most popular RTC, and works best with 5V-based chips such as the Arduino. \u003cbr\u003e\u003cbr\u003eThis breakout board is a kit and requires some light soldering which should only take about 15 minutes. \u003cbr\u003e\u003cbr\u003e\u003cspan style=\font-weight: bold;\\u003ePlease note:\u003c\/span\u003e The DS1307 is simple and inexpensive but not a high precision device.