LTWHOME Micro Filtration Media Pads Fit Rena Filstar xP Filter 733A(Pack of 50) The cotton poly filter pad is used in the last stage of filtration, and removes small waste particles from the water. Custom designed and manufactured for the Rena Filstar Filtration Systems. Enhances biological filtration. Provides efficient water flow with less clogging for long lasting filtration. Good for freshwater and saltwater environments.