BRIO STAGE 4 POST-CARBON FILTERPost carbon filter: reduces any possible residual taste & impurity from water 5 micron rating: effectively reduces impurities down to 5 microns in diameter Easy to replace: remove and replace filters effortlessly due to user friendly quick change design Convenience & value: one Brio filter gives you 40x the capacity of the leading gravity based pitcher Long lasting: purifies water up to 12 months depending on influent water quality and filter usage