The WGAS Series filter cartridges are Polyethersulfone Membrane filter cartridges for economical water grade or high purity applications. Designed for absolute retention, membranes are rated from 0.03 to 1.0 microns. These are constructed of FDA listed materials and meets USP Class VI Biological Test for plastics. With 6 square feet of media (non-flushed), their high surface area gives you maximum throughput and long service life.