STREET BASIS Z is strictly a ride height adjustable kit. This makes it a perfect setup for the daily driver looking for an increase in handling performance without compromising comfort for everyday use. For many of you considering a lowering spring + performance shock absorber combination, the STREET BASIS Z makes even more sense as we select appropriate spring rates and valve our dampers to match. No guesswork on the end-users part in trying to match one brand of springs to another brand of shock absorbers. The added height adjustment feature allows the end-user the ability to adjust ride height to their preference, something that lowering springs lack.