Saucony Kinvara 7 Boston running shoes continue to provide that lockdown fit and resilient ride you've come to love from this series. This update sees the addition of an EVERUN Heel Insert to give you even more cushion exactly where you need it most. This special edition pays homage to Boston Marathon and the MBTA's (Massachusetts Bay Transportation Authority) Green Line, which runs along the iconic marathon course. Both will soon be celebrating their 120th Anniversary. Upper: FLEXFILM™ lightweight yet strong material allows for fewer layers in the upper for a seamless, flexible feel. RUNDRY Lining combines superior moisture wicking properties with a plush feel for comfort. Padded tongue and heel collar enhance comfort. Flat laces reduce irritation.Midsole: EVERUNHeel Insert provides a lively, resilient ride while providing continuous cushioning and enhanced energy return properties. EVA+™ High Abrasion EVA foam is a lighter alternative to rubber in the midsole and outsole construction. Removable insole.Outsole: TRI-FLEX provides increased force dispersion over a greater surface area while also delivering optimal flexibility and traction. iBR+™ is 33% lighter and provides more cushioning compared to standard blown rubber. XT-900™ premium carbon rubber outsole material offers exceptional traction and high-wear properties.