The 2100 is the next best shoe since sliced bread. ASICS® 2000 Series is the most popular line of shoes in the running industry. This newcomer offers the same quality and performance as its predecessors, with the I.G.S.® lined componentry providing support, DuoMax® and SpEVA® cushioning.- Impact Guidance System (I.G.S.®)- ASICS® design philosophy that uses linked componentry to encourage optimal gait while allowing for natural foot movement from heel strike to toe-off- DuoMax® ensures that the shoe maintains proper support for the foot during the critical transition from heel strike to toe-off- SpEVA® Midsole Material provides superior shock attenuation along with a cushioned ride and enhanced durability- Space Trusstic System™ -an advanced system that creates a pocket between the Trusstic System® device and the midsole, allowing for greater midsole deformation and more efficient foot functioncolors:peri-blue/white, green/white or black