Now, get the Birkenstock comfort you crave even in your work boots and hiking boots. A full-length semi-rigid polycarbonate insole is contoured to support your arch and cradle your heels for comfort that lasts throughout your active day. A moisture-wicking mesh liner provides breathability. A special forefoot area is flexible and improves shock absorption during high impact activities. Thin enough to wear with any casual or athletic footwear and ideally suited for boots. Recommended for anyone with low to average arches. Available in medium width only.