Search for "Sophia by leo" and you'll find all kinds of little tidbits. Also search for the tsaf. The wire or coil usually just goes by the letters like "R/NR" or similar.
It's just regular resistance wire in the middle and non resistance wire welded on the ends. Current through resistance creates heat. By having leads with virtually no resistance you keep the heat localized on the coil. It's good for tight spots and burny grommets (looking at you again kanger).