Lees Cartridge Premuim Dispenser 2-Pack is an easy-to-install cartridge with twice the high-grade activated carbon of our Standard Disposable Carbon Cartridge. Lees Cartridge Premuim Dispenser keep tanks sparkling clean! They are designed to fit our Economy Original or Premium Undergravel Filters. for optimal performance it is recommended that you replace your cartridges every 2-3 weeks. Contents: 2 Premium Carbon Cartridges Lees Premium Disposable Carbon Cartridges: 2 Pack - Aquarium Filter Cartridges. Packaging 2/Blister card.