This is a limited edition color exclusive to Koike Sports and On. The women's version is sold out and is a rare color that is difficult to obtain as it is not available on the market. I love the color yellow and bought it as a stock item, but my daughter didn't seem to like the color very much, so I am selling it. The following is from the On official website and Koike Sports. Cloudspike Citius 2: A mid-distance track spike specifically designed for 800m to 1,500m races. It delivers speed with excellent rebound and propulsion. The Cloudspike Citius 2 was developed in collaboration with On's elite track runners. It meets all the unique needs of mid-distance track athletes, achieving extremely high rebound, speed, and power. Recommended for 800m-1500m competitions, this mid-distance spike focuses on rebound to achieve an aggressive run. Light Support The ultra-lightweight, one-piece mesh upper is breathable and releases uncomfortable heat. The cage structure secures the foot, providing high support and a competition-level fit. Energetic with Every Step The tuned HelionHF hyperfoam midsole converts stored energy into powerful propulsion. Feel the Power The glass fiber reinforced nylon, half-length Speedboard evenly distributes force, enhances rebound, and enables powerful kicking. Overwhelmingly Fast The Cloudspike Citius 2 unleashes your potential. It demonstrates extremely high rebound and challenge in 800m-1500m races. Sole thickness: Under 20mm Replaceable pins 7mm needle pins, 6 per shoe / pin wrench included Usable for track races of 800m or more Suitable for 800m-1500m competitions Weight: Approximately 156.6g (26.5cm/one shoe)