H&R 17-21 Mercedes-Benz C43 AMG Sedan W205 VTF Adjustable Lowering Springs (w/AMG Ride Control)H&R VTF kits are designed to work with your vehicles original electronic shocks. Specific rate springs provide superb ride quality and comfort, while reducing body roll, offering more balance and control to your ride. H&R VTF packages are made with light weight, high tensile strength spring steel alloy, feature a limited lifetime warranty, and are TUV approved.