Cascade Pro-Z Filt-A-Pack is a convenient ready-to-use nylon mesh filter bag filled with Zeolite. The laboratory-quality ammonia-removing zeolite crystals removes harmful chemicals, toxins, odors, discolorants and other contaminants. Can be used in Penn-Plax Cascade Canister Filter, Eheim ECCO, Eheim Pro & Pro II, Aquaclear 500, and FilStar Canisters. Contains two 8 oz. packs. Shipping weight: 1 1/5 lbs.