This material combines the lively properties of an Open Cell Sponge core, completely encased in tough weatherproof jacket of Nylon reinforced Neoprene. The entire section is pressurized to eliminate air during the lamination process, thus ensuring the finished packing maintains its integrity and is not subject to unwanted deformation. Open cell core provides more “lively” seal, while jacket offers complete weather resistance - together, they provide Excellent Longevity.