The Arduino 4 Relays Shield is a solution for driving high power loads that cannot be controlled by Arduino’s digital IOs, due to the current and voltage limits of the controller.
The Shield features four relays, each relay provides 2 pole changeover contacts (NO and NC); in order to increase the current limit of each output the 2 changeover contacts have been put in parallel. Four LEDs indicate the on/off state of each relay.
The Arduino WiFi Shield connects your Arduino to the internet wirelessly.
The Arduino WiFi Shield connects your Arduino to a wireless network using the 802.11 wireless specification (WiFi). It is based on the HDG204 Wireless LAN 802.11b/g System in-Package. There is an onboard micro-SD card slot, which can be used to store files for serving over the network.