These Mt. Maddsen lace-up hiking boots feature Premium Timberland® leather, ReBOTL™ fabric lining containing at least 50% recycled PET plastic, a compression-molded EVA midsole designed for comfort, and rubber lug outsoles designed for traction. By purchasing this product, you are supporting Leather Working Group certified tanneries https://www.leatherworkinggroup.com/ The ReBOTL™ material used in Timberland® apparel contains at least 40% recycled PET (recycled polyethylene terephthalate, the stuff plastic bottles are made of). The ReBOTL™ material used in Timberland® footwear and accessories contains at least 50% recycled PET. (Excepting trace materials) A comfort system, adopted from Timberland PRO, designed with shock-absorbing, geometrical technology that returns energy back to the foot to deliver all-day support and comfort.