Item Type: Aquarium Ball Filter Material: PVC + Polyester Fiber Product Specifications: 30 Pcs for Pack Product Size: Filter Ball Diameter: Approx. 4.2cm / 1.65in Mesh Bag Size: Approx. 32.5cm x 22cm / 12.79 x 8.66in (There is an error of 0.1-0.5cm) 1Porous structure, adsorption capacity, accelerate the decomposition of organic matter and the transformation of harmful logistics. 2It is flexible, compressible, has a large gap rate, and can absorb impurities in the water. 3The filter ball uses polyester fiber to make wool into a spiral to increase the surface area. 4It is suitable for the adsorption and removal of impurities in fish tank and aquarium water to purify. 5Cultivate nitrifying bacteria, strengthen beneficial bacteria, and decompose toxic substances.1. Please allow 1?5mm error due to manual measurement. Thanks for your understanding. 2. Monitors are not calibrated same, item color displayed in photos may be showing slightly different from the real object. Please take the real one as standard. 1 Pack x Filter Balls&nbsp (30Pcs) 1 x Mesh Bag