These are a true progressive bump spring set-up in a small package. The outer spring determines the initial rate of the stop until it engages the inner spring at which time the rate becomes the combined rate of both springs. With several rates of outer and inner springs to choose from you can create a wide range of progressive combinations.
 
2.5" - 5 spring progressive kits come complete with 5 outer and 3 inner springs, 2 sets of retainers, packer washers and shaft spacers. Everything you need to install and run in 1 box.
 
Kit contains 5 - 2.5" outer springs and 4 - 1.5" inner springs. You choose the outer rates you want.
 
Inner springs are 1 of each 200, 300, 400, 500 pound rates. 
 
Available for 1/2", 9/16"/14mm shaft size.