0.5 MICRON RATING: With a nominal filtration rating of 0.5 microns, our quality NSF Carbon filter reduces fine sediment particles and chlorine taste & odor from tap water 20x4.5 NOMINAL: 20” BB filter made with CTO coconut shell carbon filter media NSF CERTIFIED: This filter cartridge is tested and certified by NSF International to NSF/ANSI Standard 42 for material requirements only QUALITY REPLACEMENT: 20” x 4.5” PAC (Powdered Activated Carbon) water filters, compatible with CBC20-BB / 155312-43 FloPlus-20BB / 455906-43, SMCB-4520. SpiroPure SP-CBR2-20BB 20x4.5 CTO Coconut Shell Carbon 0.5 Micron Replacement Water Filter Cartridge