Extremely buoyant and durable, the billet material is composed of millions of tiny non-interconnecting air cells – each serving as an independent buoyancy chamber. These billets won’t lose their buoyancy, even if punctured. It takes only 1 cubic foot (0.03 cubic meter) of Styrofoam™ Brand Buoyancy Billets to float 55 pounds (25 kilograms). One of the first uses of DuPont Styrofoam was as flotation material for the use of the US Coast Guard. Although DuPont Styrofoam brand extruded polystyrene foam is now used in many more applications, it is still available as buoyancy billets for the construction of floating piers and docks, where its closed cell structure ensures good flotation and low water absorption. - DuPont Styrofoam Buoyancy Billets 7 in. x 20 in. x 8 ft. Supports 425 lbs.