I'm looking for a specific type of electrical wire, I'm sure most you in (at least in the US) have seen / touched or even spliced it before.
It's that wire you'd find on HID ballasts, it is silver or zinc coated copper. It is stranded, however, there are usually no more than 7-8 strands inside of thicker size. The insulation is I believe rubber, or perhaps silicon as it feels very soft. They can be found in 12, 14 and 16AWG.

I need a spool of this as I'm doing a wiring project at home. I love this wire because the thicker and fewer strands let it retain its shape while being very flexible and easy to work with, it's weatherproof, and the rubber is thick.

Note: I've heard it can be called sometimes "hookup wire" or "appliance wire" but this is such a broad term that it doesn't help much. I'm looking for a code, a model number, a specification or manufacturer.

Best example I can find in hi-res up close is this picture of an outdoor rated socket.

Silicone insulation was, as far as I've seen, used with tin plated core wires.
Plus the wires inside used to look somehow "dirty" (no idea if that is some separator preventing the sleeve to hard stick to the metal or just some surface reaction between the silicone and the wire during manufacture).
So if the wires you are looking for looked that way, they were most likely silicone and are sold labeled like that.

A lot of wire types are sold labeled silicone, I need something more specific for riding that particular wire. I'm sure it's got a type / number / code / denomination otherwise I think a lot of engineers would rip their own head off if everything we use and parts we order was named so generically.