Air Duct Screen and Carbon Filter for 4 Inch Ducts; Atomic Innovations

Does its job, filters my incoming air pretty good

Used as pre-filter on my fresh air intake system (Merv 13 filter box & duct fan). Fit perfectly inside 4” flex duct which was attached to wall penetrated vent duct. Plan to clean and reuse.

If you live far away from any city ,like I do,chances are you have a septic,and your septic has a vent {or else it wont work}. Well we don't want that ,but every so often that vent will remind you what it's attached to, PHEW in no uncertain terms PHEW !!! Most vent pipes are 4in, which is great because this item is just the right size for the job.. If your vent is straight out the ground with a PVC rain cap you're in luck ,2 90 degree elbows to make a "gooseneck " is even better,and one 4in coupling to join the elbows together. These fittings you can get on Amazon along with a bag of. fish tank granulated charcoal and a charcoal pad type filter. Bear with me we're almost there. Disconnect the last elbow,{or buy2 if needed} insert the 4 in duct filter into the bottom leg of the down pointing elbow ,and secure with 2 screws 1 per side, use an elbows to press down on the charcoal pad, and cut out out a 4in circle. Now its assembly time , pour the loose charcoal into the down pointing elbow, ,press the pad circle on top of the loose charcoal and reassemble the gooseneck ,add 2 more screws to the joint where the elbows are joined and you're assembly is complete . The triple dose of charcoal will tame even the most ferocious, exotic "fragrances" Lastly you can replace the mat circle and the granulated fill when your tank is pumped or recharge it by applying heat with a hair dryer. NOW you're done. PS it took longer to write this, than it took to do it.

Well made and works to filter intake air. A bit pricey but it works. Probably wouldnt buy again at the price point. One positive is the rivets can be drilled out to replace the filter material. Just need three screws.

I added a small return to an existing system, bringing it into a primary return plenum downstream from the primary filter. This filter will prevent foreign particles from entering the hvac unit. I did drill two holes for readily accessible screws should I need to take it off and clean out any accumulation (not expected, but being able to take it off is appropriate).

It's good for the price it does keep dust and pathogens out the grow tent good air flow only issue I got is it gets dirty fast and have to clean it often

These are perfect. I p[laced it in the duct work of my grow tent. Helps keep my home smelling fresh. Very easy to install and made out of good materials. This filter gets an A for all around usefulness. I will be buying more, a lot more.

I have this connected to a 4” x 20’ long hvac hose with an extractor vent to purify the air when I smoke my cigars. It does the job for me. The only trouble I had was installing it to a 4” air duct. It fits very tight. I wish it was around 3.95” so it can slide right in without having to force it inside the vent.