Features - Easy to use biological filter for tropical aquarium fish Aquarium filter sponge for efficient biological filtration - Great biological filter for breeding or spawning aquariums Multi-strata design provides large surface area for optimum filtration - Provides the ideal location for bacterial colonization - Operated by an air pump to create numerous minute bubbles to increase dissolved oxygen content - Supplying the water much needed oxygen - Most fit to external or top filter as prefiltration unit - No deads spots in cylinder foam offers increased filtration - Various types of installations are possible - The sponge material is easy to clean Quiet operation What's in the box 1 x XY-2891 Air Driven Biochemical Corner Sponge Filter for Aquarium