
GermGuardian FLT4100 Filter
Score: 85/100
Nispira HEPA Replacement Filter
Score: 75/100Rankings

The GermGuardian FLT4100 is a genuine combination replacement filter featuring True HEPA filtration and activated carbon to capture 99.97% of particles down to 0.1 microns. It simplifies maintenance by combining pre-filter, HEPA, and carbon layers into one unit, though it carries a premium price. It is best suited for pet owners and allergy sufferers seeking warranty-compliant parts.

The Nispira AER1 is a replacement air filter designed for Holmes and Bionaire air purifiers, featuring a two-stage filtration system that combines HEPA technology with activated carbon. It captures airborne particles as small as 0.3 microns while simultaneously removing household odors, smoke, and volatile organic compounds (VOCs). The product is available in various pack configurations to suit different maintenance schedules.
| Attribute | ![]() | ![]() |
|---|---|---|
6 monthsbest | 6 monthsbest | |
99.97 percentbest | 99.97 percentbest | |
| ↓ lower better | 0.1 micronsbest | 0.3 microns |
3best | — | |
| ↓ lower better | 0.2 lbs | 0.001 lbsbest |
1best | 1best |
Click an attribute name to sort · Green = best, red = worst (relative to this comparison)
| Attribute | ![]() | ![]() |
|---|---|---|
Compatibility & Fit(1) | ||
Compatible Models | AC4100, AC4100CA, AC4175, AC4175W, AC4150P, AC4150BL, AC4150B, AC4150PCA, AC4150BLCA | Holmes HAP242-NUC, HAPF30AT-U4R, CAP531-U, CAP529-U, HAP240, HAP242, HAP412, HAP422, HAP424, HAP706, HAP716, HAP9240, HAP9242, HAP9412, HAP9414, HAP94, Bionaire BAP260, BAP815, BAP9700 |
Physical & Packaging(2) | ||
Weight (lbs) | 0.2 lbs | 0.0006 lbs |
Dimensions | 1.5 x 8.25 x 4.62 | 1.2 x 10 x 4.6 |
Filtration Performance(4) | ||
Filtration Standard | True HEPA | True HEPA + Activated Carbon |
Minimum Particle Size Captured (microns) | 0.1 microns | 0.3 microns |
Target Contaminants | dust, allergens, bacteria, wildfire smoke, VOCs, pet odors | Cooking smells, smoke, pet odors, VOCs |
Pre-Filter Type | Pre-Filter | Carbon Sheet |

Products in the top-left offer the best value (high score, low price).

Search results do not contain explicit professional reviews or editor evaluations. However, broad retail confidence is indicated by the product being stocked as a recommended genuine replacement at major authorized retailers including Staples, Walmart, Target, Lowe's, and Home Depot. Guardian Technologies emphasizes that using these specific filters maintains product performance and warranty coverage.
Detailed consumer reviews or user testimonials are not available in the provided data. Retailers recommend replacing the carbon filter every three months for optimal odor reduction while the HEPA filter should be replaced every six to eight months depending on usage intensity, suggesting that consumers with high-traffic homes, pets, or smokers may require more frequent replacements.


