Most vehicles need very little rebound and every vehicle needs different compression valving, FOA has 6 general valving’s for compression- Zero, Extra Light, Light, Light/Med., Med., and Firm. For rebound we have Medium, Light and Zero. (Zero is generally spec’d when using a coilover as a “coil carrier”, and using another shock to provide your damping.) When ordering you can specify the valving you want or give us the vehicle weight, the amount of shocks per wheel and type of terrain and speed you are driving and we can valve them for you. Every FOA shock can be re-valved to meet your desires. No special tools are required.