Description: Square Appearance Design: The box features a square design that blends harmoniously with the overall layout of the aquarium, ensuring it doesn't stand out awkwardly. Stable Box Design: The overflow box is designed to securely hang on the aquarium, preventing displacement of the water pipe fittings and reducing the risk of accidents. Anti-Backflow Design: It comes with an anti-backflow design that effectively prevents water from flowing back into the tank in case of power outages or similar situations. Adjustable Water Flow Direction: The water nozzle can be adjusted 180 degrees to flexibly control the direction of water flow. Material: Made from acrylic material, this box is sturdy and long term, ensuring it can withstand regular use in your aquarium setup. Specification: Material:Acrylic Size Chart: 15cmx9.8cmx21cm/5.91inchx3.86inchx8.27inch Package Includes: 1xOverflow Box Note: Please allow slightly errors 1-2cm differences due to manual measurement.