These replacement string wound cartridges are for drinking water and industrial applications.  It is made of polypropylene string wound on a polypropylene core.   This

4 1/2″ X 20″ filter provides optimum particulate, sediment and solids removal per micron filter rating. 

• Fits all ECS Water Recycling/Filtration Systems
• Made for maximum hydocarbon encapsulation.
• Provides optimum particulate removal.
• Made in the USA.
• Fits 20″ Big Blue Filters.
• Size 20″ X 4.5″
• Avaliable in 1, 5, 20, 50, 100 Microns.