Justin the orange wire with the black plug is the inline fuse. You can put inline either between your main power source and your relay or between the relay and the bottle heater itself. As far as adjusting the PSI Switch there is a set screw on the end of it that you use to adjust it. Screwing it in is higher pressure and out is lower pressure.
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Aaron Mick
Comp Performance Group
Technical Consultant
Justin it comes pre-set for 875-1000psi range. You could turn it up if you prefer and yes you would need a pressure gauge to do this, though I would recommend having a pressure gauge either way.
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Aaron Mick
Comp Performance Group
Technical Consultant