Changing my switch help needed

[Adammully]

I'm changing my isolator switch to a blue sea one and not sure on the wires

 

[pappajohn]

You will need to connect the two black wires together then the two red cables across the switch.... On in... One out.
Won't make any difference which way round but the top wire on the old switch to 'input' on the new one will keep it right.

Incidently, the old switch is a 400v 3 phase isolator for 3 phase electric.

 

[Raul]

I was that suggested to change the AC switch to a proper DC battery isolator, as pappajohn said, join the negatives together and connect the positive each end to each studs. That wire looks very thin, what does it feed?

 

[Adammully]

Sorted it now thanks guys think it's a switch for the solar panels