A nice touch is the PCB power relay's consistent behavior, even when line voltage dips slightly.
QTY (4) JS1EJ-6V AROMAT 6Vdc SPDT 1-FORM-C PCB RELAYS AJS134098
You will find that the PCB power relay pairs drivers and control circuits.
What stands out about the PCB power relay is how smoothly it clicks on and off each time.