OASE Pre-filter Foam Set of 6 for The BioMaster 45 PPI

The Pre-filter Foam Set 45 ppi for the BioMaster 250 350 or 600 includes six fine replacement filter foams. The combination of coarse and fine filter foams allows you to customize to meet the filtration needs of your aquarium. It is best to replace the pre-filter foam when you notice a decline in aquarium filter performance.