The Karhu Flow 6 IRE gives runners an uninhibited running experience. This lightweight running shoe is equipped with an Intense Rolling Effect or IRE. A shortened fulcrum lever creates a much quicker turnover during the run. Runners looking to reach their next PR will enjoy a fast and smooth ride. Upper: External heel counter for comfortable heel lock. Welding on the medial side for structured and supportive fit. An extended toe box for better fit. Midsole: Shortened fulcrum comfortably quickly guides the foot through the gait cycle for quick turnover. A Protect Foam compound provides cushioning while Propel Foam enhances the rolling effect. Outsole: Blown rubber forefoot and compression molded rubber heel.