Package contentsThere are 4 aquarium filters in the package, size:3.3x1.2 inch (H x W), Inner hole diameter:0.6 inch/16mm, Please measure the size before purchasing so that you can buy the right product. Aquarium filter guardStainless steel aquarium filter guard can promote gas exchange and increase the dissolved oxygen content, which is very useful for aquariums. High-quality materialsMade of high-quality stainless steel, non-toxic and not easy to break, does not cause problems with algae, is nontoxic and harmless to fish, can be used for a long time. Easy to cleanWhen 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 toothbrush. Protect Shrimp and FishThe fine holes of the fish tank mesh filter can prevent large debris and protect the fish from being sucked blocking the filter system.