The marine sources overflow box is designed to hang over the outside of your aquarium by allowing water to be siphoned back to your sump this eliminates the need for drilling holes in your aquarium water can be pumped from the sump into the aquarium and then via the overflow box back into the sumpr each unit is designed to reduce noise and features a removable safeguard comb to prevent your fish from entering the overflow box dual air draining tubes can be connected to any powerhead with a