Simple 4 mechanical single circuit relay module.
Pros: The advantage of the mechanical relay, that it completely isolates the switched high current voltage from the controlling microcontroller.
Cons:Limited switching frequency.

• up to 250VAC
• up to 5A/output
• Simple 1 port interface:
    4 inputs control the 4 relays
    LED feedback for each inputs
• Output: 2 screw terminal blocks / relay:
    Common input
    Normally open output