Tein Flex Z coilovers for the 10th Gen Honda Civic Si are an incredible value. The Flex Z kit features height adjustability, 16 level damping force adjustment, front camber adjustable pillow ball upper mounts, suspension error canceler for the stock suspension electronics, and the ability to work with the Tein EDFC controller. The twin tube shock design makes for great use on the street and can absorb a wider range of bumps and uneven surfaces. Tein puts them through a rustproofing process to ensure the durability is very high and the components will last a long time. As you change the height, the length of the stroke will not change as the shock body is the method of height adjustment, not the spring. This kit is a massive upgrade for your 10th Gen Civic Si with tons of features and flexibility to get your suspension setup just how you want it!