Challenge's Grifo XS 33 Tubular is a great choice for grass, pavement and tacky dirt and when fast rolling and cornering is important. It's built on their light and supple 260tpi hand-made SuperPoly casing with its polyester-reinforced sidewalls. And, there's an anti-puncture strip under the tread. 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. The White/Black version features a softer rubber for better grip in cold temperatures.