The capability of the Tokico D-Spec adjustable shock to be such a multi-use product, results from a sophisticated piston and valving design, combined with a unique variable-aperture bypass controlled by an adjustable slide valve. Tokico D-Spec adjustments change both rebound and compression damping simultaneously. Between the hard and soft settings, the Tokico D-Spec is infinitely adjustable. D-Spec shocks and struts are sold in sets of four. Each set includes a manual giving pointers on how to adjust the Tokico D-Spec as well as various suspension tuning tips.