- Filter BagsMultiple filtration uses require multiple filter types and sizes. Pall’s FSI™ filter bags (filter socks) come in a variety of materials and styles with a wide assortment of collar and ring types that ensure compatibility with nearly all bag vessels on the market. Most of our filter bags come standard with the patented Polyloc® sealing ring that provides a complete hermetic closure that eliminates the possibility of migration. Pall’s FSI filter bag products provide efficiency with both low cost and use. We supply higher solid loading, superior chemical compatibility, consistent quality and performance supporting the fluid processing needs in a variety of Oil & Gas, Chemical, and Industrial applications.