What is it for? Rapid-fire rebound and a vibration-free, cushioned ride. Sonic 5 Balance is lightweight and balanced for a broad range of runners, featuring Optivibe technology to keep vibrations low and energy return high for smooth, more comfortable transitions. A soft and enveloping mesh upper and pillowy tongue and collar construction hug and support your feet for miles. Benefits? Reduce Vibrations Optivibe™ cushioning helps limit vibrations with the aim of decreasing muscle fatigue, while continuing to deliver a responsive ride. Responsive Ride Delivers that bouncy, springy feeling each time you push off the ground. Balanced Transition The Geometric Decoupling axis is centered to deliver a balanced, effortless forward transition from contact to propulsion. Features: Geometric Decoupling™:  Geometric Decoupling™ works with the foot to provide guidance for an effortless and efficient heel-to-toe transition. Optivibe™: A combination of foams, one to dampen, one to propel. This was developed to reduce vibration upon foot strike aimed to decrease muscle fatigue without affecting the overall ride SensiFit™: SensiFit™ cradles the foot from the midsole to the lacing system, providing a secure, snug, and virtually customized fit all around the foot. Road Contagrip®: Our Road Contagrip® combines flat, wide lugs for grip on flat, hard surfaces, with a compound that balances durability and adhesion. Ideal for road running. Engineered Mesh: Engineered mesh is a structure that varies the weave to offer more support and durability or flexibility and breathability, according to the specific needs of the shoe. Molded EVA sockliner: A molded sockliner that improves comfort by mimicking the foot's natural shape. Details Inlay sole: Textile /SyntheticLining: TEXTILE 100%POLYESTEROutsole: RubberUpper: Textile / Synthetic MCLDrop: 8 in mmHeel stack height: 28 mmForefoot stack height: 20 mmWeight: 236 gLacing system: Regular laces