First introduced in 1989, the Si-18 International is an iconic representation of K-Swiss' dedication to honoring athletic heritage while optimizing performance for future design. This reissue of the award-winning style combines elements of classic K-Swiss Tennis Shoes, such as a premium leather upper, with innovative engineering that introduced the world to the groundbreaking Silicone Formula 18 for which the shoe is named. Flag accents adorn the heel and tongue to honor the host countries of the Grand Slam, the biggest tournament in Tennis Shoes. Along with a vintage ski boot-inspired D-R Cinch lacing system and an asymmetric single-density PU midsole, the Si-18 International Heritage provides unmatched comfort and support in a timelessly recognizable silhouette.