10" Big Blue Melt Blown Poly Filters Big Brand 1000 Series Filters- 100% Pure Polypropylene, Zero additives! Big Brand Water Filter high capacity spun 100% pure polypropylene filters are made from FDA approved pure polypropylene resin. These filters contain no silicone or lubricants like string wound filters. Big Brand spun poly filters feature a unique thermally bonded microfiber construction process. The result is a high capacity pure polypropylene bacterially resistant filter all at a very reasonable price! These filters have more bacterial resistance than our high capacity pleated filters above.