Specifications:

• With this Ethernet Shield, your Arduino board can be used to connect to internet
• Genuine Microchip's ENC28J60 SPI Ethernet controller and HR911102A RJ45 socket
• Open-source TCP/IP protocol stack as an Arduino library.
• Web client application to use Arduino as a distributed network sensor
• Dimension: 5.9cm x 3.5cm (2.32 x 1.38 inch).

Download :
datasheet