The CST Blackjack features a fast-rolling tread pattern with small, tightly spaced knobs for optimal rolling resistance Evenly spaced knobs work well on medium and hardpack conditions SC - Single compound, one compound throughout the tread optimized for longevity and performance Standard 26x2.1 559 Wire Bk/Blk 65 670 27 SC NoUPC/EAN/GTIN: 6933882517806