Metal Filter Tube Made of Durable Stainless Steel and Acrylic, Won t rust Easily. They are Sturdy, Compact and Resistant to Deformation. Are Great for Aquarium fish Tank, To Promote gas Exchange and Increase Dissolved Oxygen Levels. Delicate Mesh Size Avoid Inhalation of Weak Shrimps. Tiny Animals like most Freshwater Shrimp, Invertebrates, As well as Small fish and fry are at Risk of being Sucked into the Large slots on most Standard Intake Strainers. Easy to Clean When Cleaning is Required, Simply Brush any Accumulated Debris off of the Filter Guard with your hand or a soft Brush of some sort like a Tooth Brush. Easy to Use The Black Rubber part is Extendable, Cover the Sponge onto the water Inlet of the Filter Guard Directly. They can Easily Connected to the air Inlet of the Filter, Such as Filter, Filter Tank and other Related Filter Equipment. Quality Promise You will Get 2 Pieces of Fish Tank Filter, The Inner Diameter of the Stainless Steel Fish Tank Filter is 16mm, Outer Diameter is about 30mm. If you have any Questions, Just Contact us, And we Will Offer the Best Quality Services and Products For our Dear Customer.