Not all runners are comfortable with the UltraBoost ST's weight. If you're looking for something much lighter, the brand's Adizero Boston Boost 6 takes things down to a pleasant 8.6 ounces. The Boost foam returns in this model to absorb impacts and protect your arches, and the Torsion System continues to work as it did in the UltraBoost ST. Since you'll likely be using these for competitive runs, you'll appreciate the upper's breathable mesh lining, which reduces moisture.