Ethernet card that allows you to connect Arduino to Internet. It is based on Wiznet W5100 ethernet chip and supports up to four simultaneous socket connections.
The Ethernet shield has a standard connection RJ - 45, with an integrated line transformer and Power over Ethernet enabled. It’s compatible with Arduino Duemilanove (168 or 328), Uno and Mega (1280/2560) (using the Ethernet library).
The module includes a practical reset button and an SD card reader, which can be used to store files on the network
Working voltage: 5VDC
Internal buffer: 16KB
Connection speed: 10/100 Mb
Connection with Arduino on SPI port
For more information download datasheet.