On board Real time clock (RTC) keeps the time going even when the Arduino is unplugged. Note: The RTC requires a small coin cell battery (not included). The board will still operate without the coin cell battery. Once installed the RTC battery will last for years.
Adafruit libraries and example code for both SD and RTC mean you can get going quickly
Prototyping area for soldering connectors, circuitry or sensors
Works with Arduino UNO, Duemilanove, Diecimila, Leonardo or ADK/Mega R3 or higher. ADK/Mega R2 or lower are not supported.
Requires soldering of header pins