Vans Zahba (Black/White) The outsole is made with SickStick natural rubber sourced from farms that follow proven sustainable practices with the intention of reducing impacts on people and the planet. The cupsole is combined with a flexible dual-density VR3Cush midsole made with at least 50% biobased EVA foam partially derived from sugarcane in accordance with ASTM D6866-16. The dual-density zone is made of at least 50% biobased foam with an all-new ImpactWaffle tread. The 98% Recycled Foam Sockliner means additional comfort added on top of a molded midsole.