Filter Max 3 PrefilterThe Filter Max Prefilters provide filtration of water before entering the main filter. They prevent debris from clogging the filter media and at the same time provide biological filtration. These prefilters Can be used with most outside power filters, canister filters, and powerheads. Each prefilter includes three universal adapters for use with various main filters intake tubes. Filter Max 3 PrefilterThe Filter Max Prefilters provide filtration of water before entering the main filter. They prevent debris from clogging the filter media and at the same time provide biological filtration. These prefilters Can be used with most outside power filters, canister filters, and powerheads. Each prefilter includes three universal adapters for use with various main filters intake tubes. Product code: 4795Item No. FT-FM1930