Vivobarefoot Primus Ludo Hi Unisex Kids 11.5, Recycled MaterialsSHOP UK Overview Vivobarefoot Primus Ludo Hi Unisex Kids 11. 5, Recycled Materials gives growing feet the space and sensory feedback they need. Vivobarefoot's kids range is built on the same barefoot principles as the adult line wide toe box, zero drop, thin flexible sole but sized and tested for children. Barefoot is best for growing feet, even in winter. The Primus Ludo Hi is a water resistant, vegan* toddlers' sneaker boot, designed for year round