PREFILTER CARTRIDGE ("A" Filter)0.2 micron element 2.68" OD x 9.59"For use in single prefilter system or as filter A in dual prefilter systemModel(s) This Part Fits: System 1 (89A1), System 1 (90A1), System 1 (90A2), System 1 (90B1), System 1 (99A1), System 1 (99A2)