they are to be used with different rockers. the package is telling you which one to use for which. the rockers for the truck are different lengths for different terrain
you said the part its connected to says progressive 2? then the package on the right is the one you need to use
Originally Posted by acefreecell
Progressive 1 = Full linear travel over whole movement - for the basher, great for jumps and very rough ground
Progressive 2 = Same as above, but goes more logrothmic (gets harder to compress) towards the end of the travel - suited for a mixture of smooth and bumps
Progressive 3 = As above, but more pronouced at the end - suited to smooth tracks