EPDM O-Ring 4253 is approx 1″ ID and fits all Aquafine® UV Disinfection Models WITHOUT Ozone.O-Rings should be replaced with each lamp change out (2 per lamp).O-Ring used in Aquafine® models DW Series, CSL Series, SL Series Disinfection, SL Series TOC Reduction, MP Series UV Disinfection, MP Series TOC Reduction, SL Series.
