Everything You've Always Wanted in a Boot...and Less. It's simple. Our 2021 3mm Custom is the lightest, most high-performance piece of aquatic footwear in the world. Our most affordable Custom Series crushes competitor's top-of-the-line boots with instant response, barefoot feel, unmatched durability, and perfect custom fit that makes you forget you are wearing booties. Our ongoing obsession with improving our products led to a completely redesigned neoprene upper on the Custom series, featuring our exclusive "EZ-O" cuff. The EZ-O cuff is a seamless O-ring against the leg, a design proven to greatly reduce water entry. Unlike other O-Ring designs, the EZ-O features a much larger neoprene panel, allowing more stretch in the opening and making the boots easier to put on and take off. Sizing Tip: Order your regular shoe size or 1/2 size down. For example, if you are a size 10.5, order a 10. Women should order 1-1.5 sizes lower to convert from Men's sizing. So if you are a Women's 8, order a Men's 7. If you are a Women's 8.5, also order a Men's 7. NOTE: If your feet are exceptionally narrow or low volume, you may want to size down even more. Recommended Water Temps: 50-60F. Key Features/Benefits Heat-moldable with boiling water for the perfect custom fit. Patented seamless Thermo-Form sole for next-level comfort, warmth, dexterity, and durability. Internal split-toe locks your foot inside the boot for precise response. Super-tacky and flexible 1mm vulcanized rubber sole pods for barefoot board feel, grip, and abrasion resistance. 3mm mid-stretch neoprene upper with GBS (Glued/Blind-Stitched) seams and external LSS (Liquid Seam Seal). NEW EZ-O cuff for improved flush-seal with easier on-off than traditional O-ring seal. 3D silicone-print cuff band reduces stretch and grips wetsuit leg to fight flushes. NEW softer two-tone plush quick-dry lining retains heat with improved air-flow and comfort. Includes a pair of knit Solite Heat Booster socks for added warmth, comfort, and easy on/off.