They look like the latter (black) set above.
BUT, I can tell you this, they ARE linear rate springs (IF that is what you were getting at), at least according to the Swift techs I spoke to who swore this up and down!
They only 'look' like progressives because those bunched bottom coils of their springs act like a separate 'tender', or 'keeper' spring would on a threaded, small diameter, coil over spring, and NOT as an actual softer/'dual' spring rate would on a progressive spring.
Again, this is from Swift themselves, so believe it or not.
I called them with the express purpose of asking if these were progressive rate deals or not (since yes, like you, I'm guessing, they looked like they HAD TO BE progressive rates), as IF they were progressive, I would rather keep the factory supplied deals.