PRICES MAY VARY. Flexion Fit Upper: Proprietary upper which provides form fitting comfort without sacrificing support. PGuard Toe Protector: Enhanced toe durability. I.G.S (Impact Guidance System) Technology: ASICS design philosophy that employs linked componentry to enhance the foot's natural gait from heel strike to toe-off. AHAR Plus Outsole: Strategically positioned in critical areas of the outsole, this exceptionally durable compound is 50% more durable than standard ASICS High Abrasion Rub