Eshopps Hang-On Overflow BoxThe overflow box effectively transports aquarium water to under cabinet sumps, refugiums, or wet dry filters. High quality overflow boxes feature bulkhead fittings for secure and convenient installation. U tube style compact overflow boxes are designed to fit between your tank and your wall to maximize space usage in your aquarium setup. With only 3 in. required between your tank and your wall, these boxes are excellent for optimizing space. Each box