Omnipure (Q5586) - 10" x 2.5" Q-Series Twist Off GAC with Phohsphate Filter - Scale InhibitorOmnipure Q Series Q5586 10" x 2. 5" GAC + Phosphate Scale Inhibitor Twist off coconut shell carbon filter with polyphosphate for chlorine reduction and scale control Twist Tap System 2000 Gallon Capacity Scale Inhibitor Food Grade Polyphosphate The Omnipure Q5586 combines granular activated carbon from coconut shells with food grade polyphosphate to address both taste issues and hard water scaling in a single 10" x 2. 5" cartridge. The built in Twist