SODIAL(R)Filtration Foam Aquarium Fish Tank Biochemical Filter Sponge Pad Mat 50x50cm Black Thickening Biochemical Filter Sponge, tough and durable. Size: Approx 50x50x2.5cm (L*W*H) Moderately hole, can cultivate high density nitrifying bacteria Can be used repeatedly after cleaning Package include: 1Pcs Aquarium Filter Sponge