The Prolimit hydrogen unisex boot is 5.5Mm thick and makes sure your feet stay warm in fall/winter conditions. The natural rubber reef sole makes you feel like you are walking on bare foots. This boot has a dry seal ankle cuff and blind-stitched seams so it can keep the water out. The boot has a reinforced heel for extra support. The neoprene is 5.5Mm thick and anti-allergic.