Ideally, when a shock absorbs a bump, it shouldn't exert loads back into the suspension on the rebound stroke. This leads to a stiff ride, and adds unwanted spring rate. To prevent this from happening, QA1 shocks use a twin-tube, non-gas design. Oil travels through the shock body to control the movement of the rod, and a deflective disc valve attached to the bottom of the rod manages how much oil flows between the bottom and top halves of the shock. Precisely controlling this valve is what gives QA1 shocks such a wide range of adjustability. It's literally NASCAR technology for the street.