Ethernet W5100 Shield Network Expansion Board w/ Micro SD Card Slot for Arduino Ethernet shield with wiznet W5100 ethernet chip Supports reading and writing mini SD / TF card Direct plug puzzle board, NO soldering needed The Ethernet W5100 network expansion module allows the Arduino to be a simple Web server With Micro SD card slot, supports SD card up to 2GB, supports 2009, UNO, mega 1280, mega 2560, Nano, Duemilanove