ASICS HEL-DS Trainer 21 running shoes give neutral runners to overpronators the perfect balance of speed and stability. You'll benefit from an improved gait cycle thanks to the efficiency of the midsole support systems. Dynamic and engaging colors bring a fresh feel to this 21st edition.Upper: Seamless Construction reduces the potential for irritation and friction caused by traditional stitches and seams. Padded heel collar enhances comfort. Lace-up front offers an adjustable fit. Heel Clutching System™ provides improved support and creates improved heel fitting environment. Midsole: Impact Guidance System (I.G.S®) employs linked componentry to enhance the foot's natural gait from heel strike to toe-off. Rearfoot and Forefoot GEL® Cushioning Systems attenuate shock during impact and toe-off phases, and allows movement on multiple planes as the foot transitions through the gait cycle. Dynamic DuoMax® Support System enhances stability and support, with reduced weight and increased platform comfort. Solyte® Midsole Material is lighter than standard EVA or SpEVA® and features enhanced cushioning and durability. Propulsion Trusstic® mimics connective tissue in the foot by creating tension as the foot enters propulsion stage. Outsole: DuoSole® Outsole reduces weight and enhances flexibility while maintaining traction and durability. Guidance Line® vertical flex groove decouples the tooling along the line of progression for enhanced gait efficiency. AHAR® ASICS High Abrasion Rubber placed in critical areas of the outsole provides exceptional durability.