filter medium; filter material
Technical term for the material used in a filter, such as activated carbon, sand, or fabric.
この浄水器のろ材は半年ごとに交換が必要です。
The filter medium in this water purifier needs to be replaced every six months.
Standard simplified kanji spelling for filter medium.
Traditional kanji spelling using 濾; less common but still seen in technical contexts.
Compound of ろ (濾, 'filter') and 材 (ざい, 'material').