AQUAEL's filter sponge cartridge is designed for use with the Hypermax external filter. This cartridge is precisely punched to ensure a perfect fit and provides the benefits of both mechanical and biological filtration for aquarium water. Specifically tailored for compatibility with Aquael's Hypermax external filter, the standard filter sponge features a pore size of 20 PPI and is positioned in the upper section of the filter for coarse filtration purposes.