Seal line bulkhead compression 20l dry bag innovative compression maximizes limited hatch space product details offering a fast and easy way to maximize the use of limited space our waterproof bulkhead compression dry bag boasts an innovative compression system a durably waterproof purgeair tm valve and stow friendly materials resulting in a space optimizing dry bag for use in boat hatches smarter compression unlike conventional systems that pull against seams our 2 strap conti