... Steel Ring 4.Size, 7"x17" PP/PE needle Felt Filter Bags were made by PP,PE,Nylon,Nomex and Oil ... Absorbent.And they were used in liquid purified with filter bag vesse together. 7"x17" PP/PE needle Felt ... 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 ...