Featured is a LED filter cartridge change indicator light that flashes when the cartridge becomes clogged with debris, providing a reminder that it's time to replace the cartridge. A great benefit of the Aqueon QuietFlow filters is the internal pump design that helps dampen noise, eliminates leaks and because it is self-priming, starts up automatically after cleaning or power interruptions. Higher flow rates also ensure a higher dissolved oxygen content for healthier, more active fish. Aqueon Replacement Filter Cartridges are dual-sided, featuring dense-floss with over 25% more activated carbon than the leading brands. These patented cartridges were designed to ensure even distribution of activated carbon. To use, simply rinse under cold water and easily install using the "FRONT" orientation tab. Aqueon Replacement Cartridges are available in: X-Small, Small, Medium and Large. Aqueon Specialty Filter Pads are designed to address common water issues. The pads are pre-cut to fit in the Aqueon QuietFlow LED PRO Power Filter Bio-Media Grid. There are three varieties available in three sizes: Ammonia Reducing, Carbon, and Phosphate Remover. Each come in a 4 Pack.