Primary (pre) air filters G1-G4 protect downstream stages and cut cost. Compare panel, pocket, roll and washable types, with specs and a practical selection checklist.
初効率 vs 中効率 vs 高効率フィルター：横並び比較
A one-page comparison of primary (G1-G4), medium (F5-F9) and HEPA/ULPA (H10-H14) air filters-efficiency, pressure drop, life, cost and where each belongs.