... or Steel Ring 4.Size, 7"x17" PP/PE needle Felt Filter Bags were made by PP,PE,Nylon,Nomex ... with filter bag vesse together. 7"x17" PP/PE needle Felt Filter Bags1).Nominal micron filter bags (#1,#2,#3, ... 3).Long time filter bags.(#1,#2,#3, ) 4).High flux filter bag.(#1,#2,#3, ) 5).Oil ... absorbed filter bag.(#1,#2,#3, ) 6).High efficiency filter bag.(#1,#2,#3, ) 7).Activated ...