Appropriate use on carpeting and songs with a high traction, the auto rotates better and drives better through corners. Fits both XB4 & XB4 2WD. Aluminum backside reduced suspension system holders with Integrated Suspension SettingsĀ (I.S.S.) enables fast & simple suspension system system geometry environment. This XRAY concept was introduced into the first XB8 and now is carried as much as the 1/10 scale XB4. Utilizing eccentric suspension system bushings put into aluminum suspension system obstructs, along side additional suspension system shims, the XB4 suspension geometry is completely modified.