Hyperflex AMP 3mm Split Toe Boot, 5 Synthetic AMP-Foam: Neoprene engineered for improved warmth and durability with focus on comfort and complete flexibility Diamond Skin Sole: provides excellent traction and protection without losing feeling and control; Miniature diamond-shaped channels ExoShell+ Membrane: A vulcanized heel lock membrane structure that connects to the upper arch strap for maximum adjustability, fit and support GBS Seams: We double-glue and blind-stitch all seams using a single-needle which does not puncture a hole all the way through the neoprene P4 Thermal Lining: Soft microfiber fleece for extra cushion and comfort with heat boosting insulation properties