This is a Ethernet shield based on the Wiznet W5100 ethernet chip,compatible with Arduino Ethernet Shield,added support to Arduino Mega. The different between with Arduino Ethernet Shield just Layout of Ethernet port location. It is based on the Wiznet W5100 ethernet chip providing a network (IP) stack capable of both TCP and UDP. The Arduino Ethernet Shield supports up to four simultaneous socket connections. Use the Ethernet library to write sketches which connect to the internet using the shield.