... ) 5).Oil absorbed filter bag.(#1,#2,#3, ) 6).High efficiency filter bag.(#1,#2,#3, ) 7).Activated carbon filter bag.(#1,#2,#3 ... ( Plastic Housing) C: PRE(PP ring of Eaton style ) PRF(PP ring of FSI style) SR4 (Steel Ring 304) SR6 (Steel Ring ... ) F: A( Absolute) N (Normal) G: U (End construction U style) V (End construction V style) H: SF (Silicon free) ST (Standard).