Odor-reducing medium carbon filter cartridges are considered suitable for Quiet's Crucial replacement Experts filter to remove odors,water discoloration,impurities and any toxins may harm your aquarium! Easy to ,so you 't have to change the filter 2-4 weeks as suggested by the experts.It is like a charm!Because it can filter out anything you 't need or anything might harm your aquarium and anything in it! Aquarium filters are very important for your filtration system. these filters to help your aquarium and,more importantly,your to last .The filter uses activated carbon to reduce any odor,water discoloration,impurities and any toxins not needed in the aquarium. color:White Material:activated carbon,sponge Package Contents: 6pcs * Filter Only the above package content, other products are not included. Note: Light and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.