Main features:
● It is directly supported by Arduino official ethernet library.
● It adds a micro-SD card slot， which can be used to store files for serving over the network.
● It is compatible with the Arduino duemilanove (168 or 328)， UNO as well as Mega (1280 / 2560) and can be accessed by using the SD library.
● The wiznet W5100 provides a network (IP) stack capable of both TCP and UDP.
● It supports up to four simultaneous socket connections.