like the title says what are they?

 

Heres a little article to help ht tp://www.tuninglinx.com/html/suspension-springs.html

Basically progressive coils react differently to bumps, once they get compressed to a certain point, they become a lot more stiffer, so smother ride intentionally on road, pot hols, small rocks, and offroading better bounce i guess.

 

Okay there are to types of coil springs constant rate and progressive rate springs.

A progressive rate coil spring is one in which the amount of force or weight that is needed to compress the spring increases as the spring gets more compressed. For example it may only take 100 lbs to compress the first few inches of a spring then it steps up to 300 lbs for the next few inches then 500 lbs for the following few inches and so on until the spring is fully compressed.

A constant rate spring requires the same amount of force to compress it from top to bottom.

Typically the progressive rate springs get you a smoother more comfortable ride and are often more flexable too.

 

cool thank you