MADHOLLY 15.7" x 59" Extra Large Cuttable Air Conditioner Filters - Cut to Fit Carbon Pad Air Purifier Filters, Washable Reusable Foam Pad Pre Filter Roll for Air Filters AC Window Unit Charcoal Sheet

I picked up the Madholly cut-to-fit carbon foam primarily to tame dust and pet hair in a couple of window ACs and to stretch the life of the main filters in a small air purifier. It’s a simple product—a 15.7" x 59" roll of black, carbon-infused foam about a third of an inch thick—that promises flexibility, washability, and a bit of odor control. After several weeks of trimming, installing, washing, and reusing pieces around the house, here’s how it actually performs.

Setup and first impressions

The roll arrives vacuum-packed and creased. Out of the bag, it looks worryingly flat. Give it time. Mine needed a solid 24–48 hours to puff back up close to its stated thickness; laying it flat and loosely rolling it the opposite way helped relax the folds. After rebound, I measured roughly 0.28–0.32 inches in most spots. It’s compressible foam, so exact thickness varies slightly, and it will squeeze thinner under pressure.

There’s virtually no chemical odor out of the package, and the foam doesn’t shed flakes. You might see a faint gray residue on your fingers after cutting—typical for carbonized foam—but it’s minimal.

Cutting and fitting

This is where the Madholly roll shines. Scissors glide through it, and a utility knife with a fresh blade makes very clean edges if you want a precise fit. A few practical tips from my installs:

• Cut slightly oversized (about 1/8" all around) so it friction-fits without gaps.
• For window ACs, the best spot is behind the front grille and in front of the evaporator coil, replacing or supplementing the stock pre-filter.
• If your appliance relies on a rigid frame, sandwich this foam behind the original frame or use a strip of painter’s tape or self-adhesive hook-and-loop at the corners to keep it flat.
• On PC intake fans or grow tent vents, a single layer provides a good balance of airflow and capture. Double layering is possible, but it will add noticeable resistance.

I cut the roll into six panels sized for two window ACs and a small purifier, with offcuts left for PC intakes. The size of the roll makes it easy to keep spares on hand.

Filtration performance

Think of this as a pre-filter. It’s designed to catch the big stuff so your main filter or coil doesn’t get caked.

• Dust and hair: Excellent for coarse debris. On a shedding-dog day, the surface goes from black to gray quickly, which is what I want to see—it means the fluff is getting stopped before it reaches the coil or primary filter. It’s noticeably better than the flimsy mesh that ships with many window units.
• Lint and larger particles: No trouble here. Range hood splatter mist? It will catch some, but I don’t recommend it as a primary grease filter.
• Fine particles and smoke: Limited. The foam is not HEPA. It won’t make a dent in fine wildfire smoke. As a pre-filter in front of a HEPA stage, though, it reduces dust load and extends replacement intervals.
• Odor and VOC reduction: Mild. There’s carbon in the foam, and I did notice a reduction of that musty “window AC off-season” odor after cleaning the unit and adding this layer. But this is not a substitute for a true activated carbon canister. If you’re trying to neutralize strong, continuous odors or VOCs, you’ll want more carbon mass than this foam provides.

If you want more odor control from this roll, doubling the layer helps a bit, but it also reduces airflow. On my Frigidaire window unit, a second layer slightly reduced peak fan speed and added a soft hiss. I ended up sticking with a single layer for comfort and noise.

Airflow and noise

With one layer installed, I didn’t notice a meaningful drop in airflow on either window AC, nor did it change the purifier’s noise profile. The foam is porous enough that at normal fan speeds, it’s not restrictive. If your unit already struggles on low speed or has a small intake area, avoid stacking layers.

Cleaning and reuse

This is the other strong suit. I set a calendar reminder to check the pads monthly. When they grayed over:

• I rinsed from the “clean” side out to push debris back the way it came.
• A small amount of mild dish soap helped with oily dust. I avoided detergents with fabric softeners or fragrances—they can coat the foam and reduce any odor adsorption the carbon is doing.
• I gently squeezed water out (no wringing) and laid the panels flat to air dry. Full dry time was a few hours.

After four wash cycles, the foam still held shape and porosity. Edges can fray a touch where the cut wasn’t clean, but functionally it’s fine. I expect each piece to last several cycles before compression and surface wear justify a replacement.

Where it fits (and where it doesn’t)

• Window ACs: Great as a pre-filter. It keeps coils cleaner and takes the brunt of pet hair and lint. If your AC has no pre-filter at all, this is a low-effort upgrade.
• Air purifiers: Works perfectly as a sacrificial layer in front of a HEPA/carbon combo. It won’t improve CADR, but it can keep the HEPA from loading with big debris.
• Humidifiers and dehumidifiers: Useful as a coarse intake screen to keep fuzz out of the machine. Ensure it’s dry before reinstalling to avoid mustiness.
• PC fans and AV gear: Good for intake dust control without a major airflow penalty. Mount with a thin frame or tape.
• Range hoods: I’d only use it as an extra layer in front of a washable metal mesh on low-heat, recirculating setups. Keep it well away from open flame or high heat and follow the hood’s safety guidance.
• Heavy odor applications: If the job is strong or persistent odors, this foam won’t replace a dense activated carbon filter or a sealed canister.

Build quality and material notes

The pore structure is reasonably uniform for a budget foam. Thickness is “about” 5/16" after rebound; expect mild variability across the sheet and compression in tight frames. The foam isn’t brittle and doesn’t crumble when cut. I didn’t encounter any noticeable chemical smell, and after drying, there’s no lingering detergent scent if you rinse thoroughly.

One nuance: the marketing implies broad smoke/VOC removal. In practice, the small mass of carbonized foam offers only modest deodorization. I’d categorize its carbon content as a helpful bonus, not a primary feature.

Value and cost of ownership

One roll yields several filters for small appliances or multiple panels for larger intakes, and each panel survives several wash cycles. That combination—cut-to-fit flexibility plus reusability—made it a cost-effective way for me to reduce dust buildup and slow down the replacement rate of pricier primary filters. If you maintain a couple of window units or run an air purifier in a home with pets, it pays for itself quickly in reduced cleanup and fewer clogged filters.

Care tips

• Let the sheet fully rebound before measuring and cutting.
• Cut cleanly with a sharp blade to minimize edge fray.
• Rinse monthly (or sooner in dusty/pet-heavy homes).
• Avoid fabric softeners or scented detergents; air dry completely.
• For odor control, consider two thin layers rather than one thick layer—test airflow first.
• Keep it away from direct heat sources.

The bottom line

The Madholly cut-to-fit foam is a practical, low-cost pre-filter that’s easy to size, easy to clean, and gentle on airflow. It excels at capturing hair, lint, and larger dust to protect coils and HEPA stages. Its odor reduction is real but modest, and it’s not a solution for fine smoke or strong VOCs. Thickness is close to spec after a day or two out of the bag, though it’s still a compressible foam, not a rigid panel.

I recommend it for anyone who wants a flexible, washable pre-filter to cut down on maintenance and extend the life of primary filters—especially pet owners, renters with window ACs, and tinkerers who like customizing their setups. I wouldn’t recommend it if your primary goal is serious odor removal or fine particulate filtration; in those cases, look for a true activated carbon canister and a HEPA-rated filter. For the jobs it’s designed to do, this roll is an easy win.