One Relay Module of 1 Channel Low Level Trigger 5V.

One Relay Module of 1 Channel Low Level Trigger 12V.

TOSR02-T - USB / Wireless 5V 2-channel Relay Module Support for temperature sensor

Solid State Relay - 8 Channels

Mini Rboard ATMega328P

ESP8266 WiFi Remote Control Module with 220V Relay

Pololu RC Switch with Relay

4 Channels 5V Relay Module

TOSR08 - Relay Module 8 channels USB / Wireless 5V

DFRobot Relay Shield  V2.1 is a completely new design which is capable of controlling 4 relays at a time.

Shield of relays for Arduino, with 2 channel mechanical relays and with 2 channel MOS switch , providing an easy way for applications low and high voltage control. 

8 relay module with ports " NC " means " Usually connected to COM " and ports "NO" means " Usually open to COM ".

A Universal Relay Board Kit with 16 Relays and Connectors included! Transformer included. The 12V DC output can be used as a power supply for other kits. Each outlet can be equipped with a noise suppressor.

Relay, as its name implies, implements a relay function. The relay can be used as a switch operated electrically through the coil to mechanically operate a switch, where it is sometimes necessary to control a circuit of another voltage and current load through a separate low power signal, such as a digital signal emitted by a mircoprocessor. Up to 30V DC and 220V AC.

Mini Relay with 6V Output, Dual Channel.

Stem Shield for your Arduino, the Velleman.

In/Out Shield for your Arduino, Velleman.

Light Sensitivity Switch Kit, Velleman.

Velleman Coded Lock Kit.