Quick wicking. Loose stacked-weave construction increases surface area on spill. Starts absorbing on contact - saves time in critical situations. These hydrophobic fibers repel water (and float) while only absorbing oils and other hydrocarbons. Large-diameter MeltBlown polypropylene fibers are randomly assembled to create a high-loft mat - allowing it to absorb up to 77 gallons per roll. Easy to see when it's fully saturated. Sold by the case.