The GEL Flux will have underpronators to mild overpronators floating on clouds with shock absorbing GEL cushioning and the bouncy SpEVA midsole. Guidance Line and Guidance Trusstic keep the ride smooth and efficient. Pronation suitability: Underpronator to neutral to mild overpronator Heel height: 22 mm Forefoot height: 12 mm APMA Seal of Acceptance. Rearfoot and Forefoot GEL Cushioning Systems: Attenuates shock during impact and toe off phases allows movement on multiple planes as the foot transitions through the gait cycle. SpEVA midsole material improves bounce back characteristics and decreases midsole breakdown. Guidance Line: Vertical flex groove in outsole decouples the tooling along the line of progression for enhanced gait efficiency and a smooth ride. Guidance Trusstic System: Integrates Guidance Line construction for enhanced gait efficiency, while providing midfoot structural integrity. DuraSponge rubber outsole: AHAR Asics High Abrasion Rubber blown rubber compound for enhanced cushioning and durability in the forefoot. Pronation is how a runner's foot rolls laterally between heel strike and toe off: Underpronation is when the foot rolls outwards, overpronation is when it rolls inwards, and a neutral pattern is when little rolling occurs.