The Purtrex Plus depth Filter is an exceptional value For general applications where long life, high purity and low change-out frequency are required. Produced through Suez Water & Process Technologies� patented Z. Plex Filter manufacturing technology, Purtrex Plus is a 100% pure polypropylene depth Filter with excellent performance. Purtrex Plus's 3-dimensional Filter matrix provides lower pressure drop and high dirt holding capacity. This translates to longer life and fewer change-outs than existing String-wound or resin-bonded Filters. Purtrex Plus's melt-bonded exterior and core ensures no media migration.