nickel plated brass.
That's perfect thanks.
Ek released an aluminium line, beginning with a kit which included 240 rad,pump res combo, fans, cpu and 10 series full cover water block.
The kit's adequate for a start but they expand the line and you can take it pretty far now with 360 rads (30mil thick now) hard-line fittings and some other stuff, though things like valves and other various bits aren't available in aluminium.
Here's what mine has grown in to
https://imgur.com/a/5YpPHgl
I'm generally happy with the result performs perfectly well assuming you're not mixing metals, generally it's only a tad behind a copper loop.
I'm currently saving for an all copper loop as I'm starting to outgrow it given the lines somewhat restricted.
Thanks again for the information on the probes, I was leary about using them given my current hardware.