Shelco Filters’ melt-blown depth cartridges are constructed of 100% polypropylene and use no additives that will cause foaming or other undesirable effects to the filtrate. Shelco’s melt-blown cartridges offer a graded density construction to provide true depth-style filtration. Made in the U.S. – Shelco Filters is ISO 9001:2015 and the melt-blown cartridges are NSF certified.