The x3 AQUA-TECH 10-20 EZ-Change FILTER CARTRIDGE #2 is a set of three internal filter cartridges designed for fish aquariums. Made by AQUA-Tech, these cartridges are specifically designed for easy and quick replacement, ensuring your aquarium stays clean and filtered. With activated carbon, these cartridges are effective at removing harmful chemicals and providing clean water for your aquatic animals to thrive. Perfect for maintaining the health of your fish and creating a clear and healthy environment in your aquarium.