Clean, healthy water: pre-filtration block and filter foam for CristalProfi e upper filter basketUse: insert into upper filter basket1 medium-pore foam plate 20 ppi, 1 fine-pore foam plate 30 ppiFreshwater and seawater resistant, no pollutant dischargePackage includes: 4 pre-filtration blocks, 1 filter foam 20 ppi, 1 filter foam 30 ppi