Marathon (tm) is purdy's most durable roller cover for maintained performance over time. formulated with an exclusive blend of nylon and polyester fabric, marathon (tm) lasts longer, paints further and provides a smoother finish with less lint. marathon (tm) is perfect for large projects as it can take wear and tear while providing consistent coverage and great final appearance. this roller cover series also has superb paint pick up and release properties for increased productivity with less trips back and forth to the bucket. use with either oil-base or water-base paints and for interior or exterior applications.