This is the Aqua Lung 3mm Echozip Boot Scuba Diving Booties Features: Ergonomic: Just like its name indicates, the Ergo boot uses our patented, anatomically correct ERGO ;shaped footbed and outsole to match the profile of your foot, preventing excess water retention and offering comfortable support. Protective: Thick yet flexible treaded outsole guards against punctures, stings, and slips. Warm: Choose from 3mm, 5mm, and 6.5mm neoprene for added warmth. Comfortable: The Ergo boot uses just a few seams, which are placed away from the widest parts of the feet to minimize chafing. Durable: Closes with a heavy-duty, non-corrosive locking zipper. Designed for warmth, comfort, and protection the Echozip boots are geared for recreational divers who want to be prepared for many conditions, from varying water temperatures to uneven and hazardous terrain.