ASICS Gel Nimbus 15 Women's Running Shoes - Safety Yellow/Berry/Purple synthetic-and-mesh FluidFit ASICS FluidFit upper technology combines multi-directional stretch mesh with stretch reinforcements that adapt to the athlete's foot, creating a truly customized glove-like fit. FluidRide provides the ultimate combination of bounce back and cushioning properties with reduced weight and exceptional durability. Biomorphic Fit upper GEL-cushioning in midsole Guidance Trusstic System This Trusstic System integrates Guidance Line construction for enhanced gait efficiency while providing midfoot structural integrity. Heel Clutching System Exoskeletal heel counter provides improved support and creates improved heel fitting environment.