The innovative Tetratec EasyCrystal Filter Pack Without Carbon is suitable for both the EasyCrystal   Filter 250 and the EasyCrystal   FilterBox 300.  With its intensive mechanical and biological filtration, the filter cartridge ensures crystal clear, healthy water. The double-layered Filter Floss Pads with a large surface area reliably remove even the tiniest particles. White side   coarse pre-filter, green side   fine filter  Fast, clean replacement: For best results change the filter cartridge every four weeks. No need to rinse the filter medium, no more wet hands  Attention: The filter cartridge must be placed into the filter with the green side facing towards the front of the unit.   3 PACK