They are progressive rear springs. Wow shipping is a killer on springs. It is 62.00 to ship. I'll let you have them for 150 shipped. That is still cheaper than buying them from Steeda for 199.99 with free shipping. And these have less than 100 miles on them. I was playing around with Eiback Pro, Steeda and the Ford springs with Koni Adjustables and Eibach pro dampers. I like the Steeda/Koni Adjustable the best but a guy made an offer and bought the GT with the Ford springs in it so I have both the Eiback and Steeda springs left over. The Eibach were too low and too firm for my taste and the Steeda was a good ride. I have Steeda Sports in my 99 Cobra also and love them.