Filter Bag Housings for the Pentek BP-420-50 Bag Filter: The Pentek BP-420-50 155392-03 bag filter fits in bag filter housing assemblies for 4" W x 18" L bag filters. Use the Pentek PBH-420-1 1" Inlet/Outlet Bag Filter Vessel Water Filter System. Use the Pentek PBH-420-1.5 1.5" Inlet/Outlet Bag Filter Vessel Water Filter System. Pentek BP-420-50 Bag Filters Also Known As: American Plumber BP-420-50 Filter Bags Ametek BP-420-50 Filter Bags Plymouth Products BP-420-50 Filter Bags Pentek 155392, 155392-03 Filter Bags USFilter BP-420-50 Filter Bags . . ( Case of 12 items for one low shipping cost )