Simple 4 mechanical changeover 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 750VAC
• up to 2A/output
• Simple 1 port interface:
    4 inputs control the 4 relays
    LED feedback for each inputs
• Output: 3 screw terminal blocks / relay:
    Common input
    Normally closed output
    Normally open output