Features:-Replacement cartridge.-Compact cartridge.-Keeps water clear and healthy.Maintenance:For better performance of the filtration system, it is recommended to change the cartridge every 2 or 4 weeks.Advantages:Retains suspended food particles and fish waste in aquarium water, clarifies and removes odors from the water.Product Details:One box of 6 pieces, one piece size 13.5X5X2CM, one piece weight about 23 grams.