Rear anti-roll bar for ball-bearing roll bar mounting system works with rear suspension arms. The anti-roll bar system is mounted to the rear bulkheads via bearings from outside for extra-smooth movement and for quick & easy changes and adjustment. The roll bar turns in ball-bearings for maximum precision and free movement. Anti-roll bar height is adjustable via a screw... quick & easy. Anti-roll bar has laser-engraved stripes (corresponding to bar thickness) for easy identification. Must be used with #303434 Aluminum Anti-Roll Bar Bushing o2.0mm - 6mm (2) Fits X4 & X4F