Perfect Replacement Cartridges: Size: 11.5 x 15.7cm. The PF-L Cartridges Are Only Suitable for Silenstream PF20, PF30, PF40 and PF75 Power Filters.Fine Carbon Filtration: Contain 3 times more activated carbon than other cartridges. Fully absorb and filter impurities or damaging substances to deodorize the water and reduce unhealthy gases.Further Cleaning: The outer layer is made of with high-density fiber. The multi-layer cotton traps debris or waste without sucking up your fish, keeping water and .Reliable Material: The carbon is well wrapped in permeable bags inside. No leakage of powders or contamination of water. And the evenly distributed cotton 't block the normal water flow.Easy to Use: Before use, rinse it with cool water to remove the outside dust, then put it completely into the filter chamber. Replace it every 2 to 4 weeks to maintain a healthy water environment.size: 11.5 x 15.7cmMaterial: Non-woven fabric + plasticcolour: whitePackage Contents: 6 x PF-L FilterOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.