Features: 1. Honeycombed Ultra-Absorption Activated Carbon Block. Solid composition, no powder, no impurities, does not cause black water. Say goodbye to the trouble of constantly changing cloudy aquarium water. 2. Filters and absorbs any dirt, stain or chemical that may be not good to the health of your pet fishes. 3. The adsorbed material is firmly controlled and oxidized to improve the filtration efficiency while extending the service life of the cubes. 4. Significantly decreases the death rate of aquarium pets. Instead, their health level is increased in the process due to cleaner water. 5. Prevents tank and water odor. Avoids the water from getting murky. Maintains the water’s PH level as well as overall cleanliness. Your fish tank will stay for months! 6. Easy to Use — Simply put it in the tank! Just wash it with soap and warm water, and then you can put it back in the tank again. Notice: 1. Applicable after rinsing. 2. Please put it near the fish tank water inlet. 3. It is not recommended to place the black mesh face up and down, causing blockage and affecting the filtering effect. 4. It is recommended to replace or rinse once every 3-6 months, and it can be washed or replaced when decolorization or efficiency is lowered. 5. Suggestion: Fish tank size: Below 60CM: 1 water purifier 60CM-90CM: 2 water purifier 100CM-180CM: 3 water purifier Over 180CM: 4 water purifier Specification: Product size: 10×10×10CM Use range: universal for fresh water / sea water Material: activate carbon Function: water purification, odor removal Include: 1/2/3/4 x water purifier