FuelCell midsole foam with approximately 3% bio-based content delivers a propulsive feel to help drive you forward. Bio-based content is made from renewable resources to help reduce our carbon footprint. Synthetic and mesh upper Bootie upper construction hugs your foot for a snug, supportive fit Toe Protect technology helps protect feet from rocks, roots and debris Rock Stop Plate outsole disperses pressure and helps protect the bottom of feet on rocky, uneven terrain