This is the Akona 3.5mm Seco Self Draining Boot for Scuba Diving Features: Seco Boots Never Sloshy or Loose Due to Filling Up w/Water Durable 3.5mm Nylon ll Neoprene Heavy Molded Sole Durable Rubber Cap on Toe and Heel Taped Elastic Top Edge for Better Wear Glued and Blind Stitched Seams Zipper Closure for Easy Donning & Doffing The Akona Seco Boot allows water to effortlessly drain out through the soles when exiting the water. Small drain holes throughout the sole that allow water to drain out. Similar to a wetsuit, water enters the boot, warms up and stays warm, upon exiting the water, the Seco boot allows water to constantly drain. Seco boots never get sloshy or loose due to filling up with water. Boot is made from durable 3.5mm Nylon ll neoprene. The boots have a protective toe and heel cap that protect these heavy wear areas, which extends the life of the boot. All edges finished with black, sewn elastic nylon binding that prevents wear and tear.