Engineered stretch knit upper: Improves breathability External back heel counter: Helps keep the foot stable and provide a more comfortable stride 4D GUIDANCE SYSTEM feature: Helps create adaptive stability for a more balanced stride Rearfoot PureGEL technology: Helps provide lightweight cushioning and softer landings FF BLAST PLUS ECO cushioning is made with approximately 20% bio-based content and helps provide cloud-like comfort: From 5Ks to full marathons, the GEL-KAYANO 30 shoe is designed to provide advanced stability and softer cushioning properties. ​​ The new 4D GUIDANCE SYSTEM helps provide adaptive stability. This helps you experience a more supportive and balanced stride during your distance training. ​​ Its midsole is revamped with FF BLAST PLUS ECO cushioning and a 4mm stack height increase. With approximately 20% bio-based content, this material helps create cloud-like softness in every step.​The new PureGEL technology is strategically positioned below the heel for a smoother ride. It's 65% softer than conventional visible GEL technology, allowing your distance training to feel surprisingly smooth.​