The Filter-MaxTM Pre-Filter provides filtration of water before entering the main filter. It provides both mechanical and biological filtration. Prevents debris such as dead fish and plant material from clogging the intake by distributing the suction evenly down the length of the sponge Maintains the biological filtration when the main filter is changed or cleaned. Can be used with most power heads as a temporary or permanent filter in aquariums, isolation tanks, holding tanks, etc. Prevents small and baby fish from being suctioned in the water. Prevents anemone and invertebrates from being suctioned into the filter. Traps larger waste particles, mechanically cleaning the water. Can be used with most outside power filters, canister filters and power heads. Includes three adapters for use with various main filter intake tubes. Easy to clean. Just rinse and squeeze under cool running water. Can be used in the vertical or horizontal position.