SPRINDEX ALLOWS FOR TOOL-FREE EASY ADJUSTMENT OF YOUR COIL'S SPRING RATE.Adjusting your shock's spring rate can profoundly improve your bike's handling and suspension. In fact, you may find yourself using different spring rates for different trails, depending on the conditions and type of trail. Or you may increase your spring rate for long climbs and decrease it for down hills. No expense was spared on the materials or manufacturing processed used. The coil itself is made of super high tensile spring steel similar to 'lightweight' springs (which is why Sprindex is lighter than regular springs) in order to handle the stress of the system when adjusted to its highest spring rate setting, as well as reduce coil mass. The Sprindex assembly is made of glass reinforced polymer. The 5 included adapters are made of slippery Delrin.Spring rate is the force required to move a spring a given distance and independent of preload. For example, a '400 lb/in' spring requires 400 pounds to move the spring 1 inch and 800 pounds to move a spring 2 inches. Preload is how much force is required to start moving the spring. Sprindex is patent pending in many countries.Follow your shock manufacturer's instructions for preload amount and sag and other shock adjustments. Do not preload your Sprindex more than 3 turns and 1 to 2 turns is preferred.Your Sprindex coil behaves like a regular coil that has a spring rate the same as your adjusted Sprindex spring rate. Adjusting your Sprindex does not change the length of the coil and so does not change your preload. Preload is adjusted normally and with the threaded ring that came with your shock.HOW DOES SPRINDEX ADJUST SPRING RATE?The spring rate of a spring is the amount of force it takes to deflect the spring a certain distance (typically pounds per inch or Newtons per mm). Spring rate is a function of 4 characteristics: wire diameter, coil diameter, material, and number of active coils. More active coils causes a lower spring rate and fewer active coils ca