Spring rubbers are great tuning tools. They give you the ability to increase spring rate quickly. Sometimes there is not enough time to change springs in between runs or sessions. The spring rubbers register between the coils on the coil spring. They are easy to install once the suspension is in full droop and the springs are relaxed. Once they are installed, make sure they are spun to the extreme bottom or top of the spring to ensure optimal performance. They are available in soft (red ring), medium (white ring), hard (blue ring), and extra hard (yellow ring).