What stands out about this design is the relay base w/ relay that snaps in with gentle pressure.
E-Max 6319220 Auxiliary Voltage Relay Nom 30A Oper 2.5A
What stands out about this unit is that it's a contactor relay, which makes handling high current much easier.
You will find that the Switch Harness Set fits common panels, saving you from custom modifications.
What stands out about the 31016 is how the model is presented without clutter, keeping things clean and clear.