Men's Caterpillar, E Colorado Work Boot. The Caterpillar E Colorado boots are the sustainable version of the iconic classic work boot. The eColorado has been developed and created with a focus on eco-friendliness, through construction and materials - better for you and the environment. LWG certified leather uppers Breathable nylon mesh linings Molded PU foam footbed Durable and lightweight PVC midsole absorbs shock Lugged rubber outsole that contains partially recycled rubber