The Cross Boss� even center tread shelf provides smooth and fast acceleration while more open side knobs help clear muck Light: Lighter weight compound conforms to trail objects while still providing a happy balance between low rotational weight and reliability FR: Fast Rolling, with WTB`s Dual DNA rubber compound that optimizes efficiency, traction and durability, A firm, long-wearing centerline tread with softer side knobs 2015 CycloCross Magazine`s Editor`s Choice - Best Clincher Tubeless 700x35 622 TBLS - Fold Bk/Skn 75 400 60 TCS/LIGHT/FR NoUPC/EAN/GTIN: 714401106758