Whiteline BBR44Z Rear Sway bar 26mm Fits BMW M4 15-20Suspension Stabilizer Bar Assembly Suspension Stabilizer Bar Assembly Sway bar 26mm heavy duty blade adjustable Whiteline Sway bar 26mm heavy duty blade adjustable WL Sway bar 26mm HD blade adj Engineered to Activate More Grip, sway bars are principally designed to reduce body roll or sway. By reducing body roll, lateral loads are spread more evenly across the tires thereby increasing cornering grip and improving outright performance. This Whiteline