Aluminum rear uprights, CNC-machined from premium Swiss 7075 T6 aluminum. Designed & recommended for high-traction conditions. Increase rear stability. Feature additional upper roll center positions for fine tuning. Roll center height can be adjusted using shims between upright and upper link. Wheelbase range has been increased and can be adjusted within a range of 4mm. Additionally black coated and laser engraved. Premium Swiss 7075 T6 For high-traction conditions Increases stability Fine & precise roll center adjustment More roll center positions Wider wheelbase range adjustment Black coated Laser engraved Fits XRAY XB4