ASICS Gel-Excel 33 Mens Neutral Running Shoes Impact Guidance System (I.G.S.) - ASICS Design Philosophy. Employs linked componentry that enhances natural gait from heel strike to toe-off. Heel Clutching System - Exoskeletal heel counter in the shoe provides improved supprt and an improved heel fitting environment for the serious runner. *** NEW *** Full-length Guidance Line - Vertical flex groove decouples the tooling along the line of progression for enhanced gait efficiency. Propulsion Trusstic - This mimics the connective tissue in the foot by creating tension as foot enters propulsion stage, getting ready for take-off. Solyte Midsole - Proprietary cushioning material that provides an exceptionally lightweight midsole with excellent bounce-back and durability.