All of the shocks we use are adjustable, either single adjustable (rebound) or double adjustable (bump and rebound). We recommend adjustable shocks because you have the ability to fine tune and/or diagnose the suspension. For most street applications single adjustable shocks are more than adequate. QA-1s are very easy to adjust, they have a knob on the side with generally 12 clicks for adjustment. Turning the knob quickly changes shock settings. This is great at the racetrack and for the person who tunes on the street. (Spanner wrench part number 4001 included with coil-overs or available separately.