Keep for fish from swimming into your overflow with the Aqua Gadget Fish Guard by Innovative Marine. The Fish Guard is molded from aquarium Safe plastic and protects small fish, anemones, snails. Plants, and other inverts from being consumed by your overflow. Dimensions: 2.68 x .50 x 1.62 inches. Fits: Nuvo 4, 8, 16. Fusion Nano 10 & 20.