Gently used Vivo barefoot Primus Flow men's shoes in color bright white neon orange. Size 42 which is a 9. Retails for $180! The Primus Flow is the newest member of the Primus family, designed for pinnacle barefoot running performance. Built for efficient and unrestricted natural movement, this ultra-lightweight runner - our lightest ever - weighs in at just 150g. Its lightweight, breathable upper made from engineered recycled mesh forgoes overlays in favour of a stripped-back, seamless construction.