The oxygen pump blows oxygen into the aquarium, when working it appears like bubbles in the water, something some people see like a good decorations. especially in still water like the fish bowls and aquarium, fish needs oxygen to have a greater chance of survival for longer period of time.fishes like the angel fishes need lot of oxygen to digest their food easily. In other words it's use to aerate an aquarium by pumping air into the water, it also break surface tension so fishes can have enough oxygen. The product in this advert does not come with hose ir air stone. Product information model sb-248a material plastic power 3w input voltage 220v flow max 3.5l / min size 9.9×6×5.5cm