The parts come in sets of left and right C-hubs including matching hardware and are black anodized and laser engraved. Generally more caster give less steering into a corner but more coming out of a turn. The new parts help to find the best setup for your given track condition or driving style.
Factory driver and designer Billy Easton posted some tips on the new parts – The more caster you run, the more on throttle steering you have, less through corner steering. Basically, they push more going into the turn, but have more on corner exit. If you have a corner entry oversteer you can use more caster to reduce that and smooth out the steering. the bi product still though is more corner exit steering. In some cases, they can make you faster due to more corner speed, but sometimes they can make you slower cause its understeering, it really depends on the track