: A primary source for both portable air purifier filters and larger HEPA-grade furnace or HVAC filters .

A value pack including HEPA filters and carbon pre-filters for HPA100/200/300 series. Available at (~$63) and Target (~$65) . GermGuardian Air Purifier Replacement Filter B flt4825 Target& more Go to product viewer dialog for this item.

: Best for finding common replacement filters for mainstream brands like Honeywell and Holmes .

Medical-grade H13 filtration for BreatheSmart 45i models. Available at (~$69) and Lowe's (~$69) .

: For general household use, HEPA 12 or 13 is standard. Sensitive environments or medical-grade needs often require HEPA 14 .