This Foreline Trap NW40 KF40 serves to prevent contaminants from entering the pump inlet and protects the system from pump fluid or particulate migration. (Backstreaming) This trap extends the life of the pump, cuts maintenance costs and helps prevent system downtime. Made of durable corrosive resistant nickel chrome finish which prevents outgassing. Interchangeable Filter Media is not included with this foreline trap but is available from this website. Filter Media options include, Activated Alumina, Stainless Steel Wire Mesh, Activated Carbon Granulate and Polyester Media.