The thick black one is memorized straight and fully activated at 100 degrees c so if you crumple it and drop it into boiling water it will shoot into a stiff straight wire, back to flex when cooled.

The thin spring is minus 0 degree so will relax in freezing conditions but also reacts with warmer temp to some extent.

It's possible to train nitinol wire to desired shapes such as a paperclip as well as make temperature operated fun or useful devices.

You'll receive 100cm straight memory and 30cm of spring in its coiled shape, not stretched out to ?cm

All the science of nitinol is out there, have fun  🥳