6 Pack - Super Micro-filtration Media Pads for Rena API Filstar xP Filters by Zanyzap Super Ultra-fine filtration Media Pads 6 Pads Per Pack Made for Rena Filstar xP Canister Filters Removes Microscopic Particles From Water Through Progressive Microfiltration Pad Place in top compartment of filter and replace at least once a month or every time the water is changed