Odor-reducing medium carbon filter cartridges are considered suitable for Quiet's Crucial Experts filter to remove odors,water discoloration,impurities and any toxins that may harm your aquarium! Easy to use,so you don' have to change the filter every 2-4 weeks as suggested by the experts.It is like a charm!Because it can filter out anything you don' need or anything that might harm your aquarium and anything in it! Aquarium filters are very important for your filtration system.Use these filters to help your aquarium and,more importantly,your wildlife to last longer.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 cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.