Open Bottom Lift Bags are very versatile light-to-medium-duty lift bags. They are excellent for sport divers, and are suitable for most types of underwater lifting and light salvage. All but the 25 lb, 50 lb and 75 lb bags have diver-actuated dump valves, and all are open at the bottom to vent expanding air as they ascend. They are economical, lightweight, and fold into a neat, compact roll for easy handling underwater. The 25 lb and 75 lb bags are made from a strong but lighter weight urethane coated nylon material that can be rolled up very small.