There is no doubt that our product can be used for maintaining the cleanness of the water because it can decompose dirt effectively. It will not affect the PH GH TDS of water quality because it is weaved with physical way without any glue. Undoubtedly, our product can filter impurities in the water effectively with fine fibers. It also convenient to clean with machine, and it will not easy to deform. It is made from polyester , it is durable to use. There are two sizes of the product to choose from. Our product is suitable for fish tank. Item Name: Ring Filter Bag Material: Polyester Features: Wear Resistant, Water Cleaning, High Density Size Details: S Size: 12cm x 30cm/4.72" x 11.81" (Approx.) M Size: 18cm x 39cm/7.09" x 15.35" (Approx.) Notes: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Package Includes: 1 x Ring Filter Bag