Upper borrows inspiration from the GEL-15-50 cross-country spike: Provides good comfort and support while keeping feet cool. Layered heel counter design improves durability against abrasions: Improves stability. Borrows the same tooling from the first two GEL-SONOMA trail shoes: Helps create smoother and more balanced movements. GEL Technology Cushioning System: Cushioning improves impact absorption and creates a softer feeling at footstrike TRUSSTIC Technology: Improves stability The outsole's grip improves traction on off-road surfaces: Improves durability.