Aggressive and unique designs comprise Series 21, and now with the optional Carbon Barrels, it’s our lightest wheel ever produced. Offering fitments for the elite vehicles, our S21-01 Carbon Series features partially-exposed titanium hardware saving optimal weight with increased pocketing.Aggressive and unique designs comprise Series 21, and now with the optional Carbon Barrels, it’s our lightest wheel ever produced. Offering fitments for the elite vehicles, our S21-01 Carbon Series features partially-exposed titanium hardware saving optimal weight with increased pocketing.