[Tumbling Filtration, Creates an Ecological Environment] Imitates the natural riverbed gravel tumbling filtration method. This new type of fluidized bed filter enables continuous tumbling for rapid nitrification. Filters collide with each other, allowing for self-cleaning and regeneration without the need to replace filter media. [Bottom Filter Cover and Filter Sponge, Double Physical Filtration] Durable and reinforced ABS housing with a protective cover that safeguards fish while allowing unrestricted water intake. Includes a filter sponge that effectively removes large particulate impurities. [Includes Air Stone, Increases Dissolved Oxygen] The air stone increases water oxygen levels and promotes fluidized bed movement, accelerating nitrifying bacteria growth and water purification. Operates quietly with fine, gentle bubbles. Note: Measurements are manually taken; please allow 1–7 cm variation. Due to lighting and screen differences, slight color variations may occur. Actual product may vary slightly from images.