Front hub carrier (casters twice), which is an optional part for BD7. The initial response of the steering is improved, which is effective on courses with many tight corners. On a high-grip road course where you are on the high side, you can prevent the high side by getting a weak understeer in the latter half of the cornering.
Compared to the kit standard 4 degree front hub carrier, the 2 degree version will provide better initial steering response. Although suited for tight track layouts with many corners, in high-grip conditions where traction rolling is an issue, the increased understeer upon corner exit may help prevent traction rolling from occurring.