Warmers brand 3mm Lo-Pro Pull-On Booties are made of 3mm neoprene (uppers) and 5mm (inner soles). The rubber outsoles provide sure grip and protection. Durable toe and heel caps enhance comfort and protection. The close fitting pull-on design allows a little water to enter boots so your feet stay warm (water in shoe warms to skin temp). Get the protection, warmth and comfort you need to enjoy paddling. Women order one size smaller. 1/2 sizes order one size larger.