Pressure Switch help

http://www.hornblasters.com/products/details.php?i=viair-165-200-psi-pressure-switch-with-relay, so that box, where do the wires go. I understand the one that goes to the compressor, the ground, and the one that goes to the fused power source. what does the last one go to?

Thanks

Twist

never mind. Travis helped me out. Thanks man, a mod can close/lock/ delete this if they want.

couldn’t help noticing that it sais so right on the label in the product image

no, I couldnt figure out what the little red wire went to. I only had 1 main wire going to the battery, understood the ground, and the wire going to the compressor. I need another wire going to a 12 volt ignition source. that’s what I couldn’t figure out. the little red wire.

Must admit Twisty, I had to look up the wiring diagram for that pesky little red one!!!

I do have a question. I have had my old one go battery, fuse, then a toggle switch that turns on and off the compressor then it goes to the setup. With this setup, can I splice into that wire and have both red ones go to it? or do I have to have the little one go to a 12 volt ignition source?