3 millimeter neoprene keeps feet warmnNylon II neoprene is very durable and stretchynBlindstitched seams lay flat on skin, Seams glued to minimize water entrynHoneycomb silkscreen bottom provides tractionnMakes a great liner for hunting or hiking boots!nKeep your feet toasty warm with Tilos's 3 millimeter fin socks. The thin neoprene does not take up excess room in luggage and are well worth bringing in your gear bag. In addition to providing warmth, wearing fin socks