【Automatic Rotation】: This aquarium outlet accessory features an innovative design that allows the water outlet to automatically rotate, driven by the water pump's power, without the need for electricity. This ensures efficient water circulation in your fish tank 【Adjustable Flowing Direction】: The multi angle adjustment capability of this accessory allows you to direct the water flowing in various directions, effectively helping to eliminate debris and maintain a clean environment in your aquarium 【Material】: Made from quality PP material, this Aquarium Water outlet fan is designed for durability and long term use in aquatic environments 【Perfectly Fit】: The outlet fan has a diameter of 45mm/1.77inch and is fit for pipe that have an inner diameter of 20mm/0.79inch or 25mm/0.98inch(optional), ensuring a snug fit for optimal performance 【Complete Set】: The package includes 2 outlet fans and a set of fittings, providing everything you need to enhance your aquarium's filtration system (note that a filter is not included and must be purchased separately) Specification:     Size Chart:  outlet fan diameter:4.5cm/1.77inch   Package Includes: 2 Aquarium outlet fans 1 set of fittings Note: Please allow slightly errors due to manual measurement and different monitors.