Hozelock BioForce Bio Force 9000 / 18000 Replacement Foam Filter Set (3 pack)
If you have the bioforce 18000 filter, two sets are required. The fine green foam is slightly smaller than the others as per the original foam specification. Hozelock Bioforce Bio Force 3000 5500 8000 Blu Grezzo Filtro Schiuma Spugna.