Arduino 4-channel 5V relay module

• This is a 4-channel relay interface board with LOW Level 5V; each channel requires a driver current of 15-20mA.
• It can be used to regulate a variety of high-current appliances and equipment. 
• High-current relays that operate on AC250V 10A or DC30V 10A are installed in it.
• It features a conventional interface that a microcontroller may directly control.
• For safety reasons, this module is optically isolated from the high voltage side.
• It also avoids ground loops when interacting with microcontrollers.