Penn Plax Cascade Canister Filter Bio-Floss replacement pads help trap floating particle matter, keeping your aquarium water crystal clear. Replacement is simple and convenient to keep your filter cleaning. Poly fiber floss pad traps floating particulate matter Convenient, no fuss replacement floss pads Fits Cascade Canister Filters Specifications: Replacement pads for Cascade 1200 & 1500 Canister Filters only. Replacement pads for other models are also available.