100% Waterproof; 5mm CR Flex-Foam neoprene liner is 100% waterproof with exceptional comfort, flexibility, shock absorption and heat retention properties; adjusts to the contours of your foot to resist blisters and chafing; Lock-down zipper closure system, with a waterproof zipper, the industry's finest and most durable technical zipper construction; Velcro stretch collar for custom fit; Scree collar to keep out debris and prevents chafing; Breathable mesh lining facilitates air circulation to improve comfort and reduce heat and moisture; Dual density comfort footbed with memory foam for long lasting cushioning; EVA midsole for lightweight comfort and shock absorption; Lugged rubber outsole for durable traction; bioDEWIX antimicrobial footbed insert topcover with NZYM for odor control and moisture management