Challenge's Grifo 33 Seta Extra Tubular boasts a tread that excels in snow, mud, grass and firm dirt. It's also built on their light and supple 260tpi hand-made silk casing for an awesome ride quality. Plus, there's an anti-puncture strip under the tread and polyester in the sidewalls for extra durability. You also get a latex tube. Latex tubes are lighter, thinner and more flexible than butyl tubes, increasing your comfort, lowering rolling resistance, and helping to prevent flats, too.