Filtrete 20x20x1 AC Furnace Air Filter, MERV 12, MPR 1500, CERTIFIED asthma & allergy friendly, 3 Month Pleated 1-Inch Electrostatic Air Cleaning Filter, 4-Pack (Actual Size 19.69x19.69x0.78 in)

I change them every three months as one member of my family has severe allergies and asthma. I am personally convinced they work better than the lower rated filters. There is a problem from time to time with fit, and their size being off by an 1/8th of an inch or so with keeps the filter from sealing. So I crunch the edge a little and that seems to solve the problem. In my experience, you can get a higher rated filter but these are just as good and don't tax the system.

Love it great value

> Well constructed. I've had no problems using these for probably 10 years or more.> In my opinion, the MPR 1500 filters are a good compromise, filtering out household dust, pollen, fungus spores, pet hair (i.e., most allergens), and are moderately effective in filtering out bacteria and viruses.> If your main concern is pet hair, then a lower MPR rated filter might be a better choice --- reducing your cost and reducing the frequency you need to change the filters. (Some reviewers claim that they have to change the filters weekly). If you have NO problem with allergens (or perhaps live in desert states), then a moderately lower MPR rated filter might be more cost effective for you.> Higher MPR rated filters (i.e., >1500 MPR) are more costly, and probably provide little improvement in air quality, unless you have someone in your household with a contagious infection; or an individual with a highly compromised immune system --- or other special situations. Higher MPR rated filters may reduce airflow though your AC condenser unit (especially as they clog up more quickly), which may translate into slower cooling, and higher energy consumption.DISADVANTAGES OF LOW MPR RATED FILTERS> Moderately high MPR rated filters (such as 1500 MPR) filters catch most of the material which would otherwise mat-up on the water film of your condenser, reducing its efficiency, which may translate into slower cooling, higher energy consumption, or shorter life of the condenser unit. In hot humid South Florida summers, this is a serious concern -- the dust, etc. that can gets through cheap AC filters mats up on moist condensers, ultimately clogging the condensers, reducing the efficiency of cooling, and therefore increasing your electrical power costs. It cost several hundred dollars to have your condenser cleaned by an AC technician --- which you'd probably need to do yearly (at least in South Florida) if you used the cheapest AC filters (say, less than 300 MPR).> Have you seen all the ads for cleaning your airducts, mostly to remove fungal spores? At probably $500 for a typical home? Better that the spores don't get to your ducts in the first place (i.e., if you use moderately-high MPR rated filters). Cleaning might work if you have sheet metal ducting--- But I (and many other people) have ducting built of insulating sheets, which are porous inside --- and I don't believe that significant cleaning (certainly not removing fungal colonies) is even possible. So, I chose what I judge to be the highest practical MPR rate filters (i.e., MPR 1500).BOTTOM LINEI believe that moderately MPR rated filters (e.g., MPR 1500), changed moderately frequently, pay for themselves in short-time electric bills and long term maintenance costs.SCHEDULE> A three month schedule works well for me. After 3 months, the filters are retaining alot of material, but are not clogged. In some seasons, I might be able to stretch to 4 months, but I stay on the 3 month schedule.> I suspect that reasonably frequent changing of the filters pays for itself in lower electrical bills (because the AC doesn't have to work as hard with clean filters). But what is "reasonable" can vary greatly from household to household, or region to region. I suggest guestimating your schedule, and when you change your filters, inspect them, and adjust your schedule accordingly.

Great Product

Furnace repair guy said they were OK & served the purpose

3M makes amazing filters. If you have animals in the house, I recommend these filters.

Spending money on filters isn't sexy. Spending money on filters that don't work is torture. Filtrete works, quality is unmatched. I'm an adult who smoked 20 years ago and now I use a vapor pen when alone in my bedroom. As a perfectionist who wants 1st quality without paying 6X retail for OEM Filters - Filtrete is my champion. Tip for newbie fan or air purifier modd-ers, you could consider the 1000 rated filters with low air flow or a 2nd layer such as carbon - and so on. You can consider higher than 1500 with Filtrete such as the 1900-2800s - etc. But the under 1000 air filters don't catch vapor and the filters higher than 1500 magically tell the vapor to make a run for the border. The vapor (smoke) will magically bypass the intake of your do-it-yourself box fair air filter or more expensive modified room air purifiers and cling onto the exhaust port from the fan and do another lap or two around your room prior to any chance of going into the intake. I'm not proud about the time I've watched analyzing this! Plus if the filters are 1900 or higher - and restrictive to start by the time you have some vapor, smoke, cooking residue, etc. etc. get into them - they are going to lose efficiency faster than I lost my high school mile time. I am a perfectionist type of gadget guy - and I don't want my bedroom or its connected sitting room dusty and showing the signs of my bad evening habit. I have (2) air sensing type air purifiers (adjust their fan to air quality), (1) IQ Air+ (expensive) that I found the 12x12x1 Filtrete 1500s stack nicely into and one large 3M/Filtrete Room Purifier (they discontinued them unfortunately) and I have found tremendous success with ONLY Filtrete 1500 Series Filters, a heavy duty set of scissors and foil HVAC/Tape. I am fortunate enough to have (4) Carrier Infinity Central HVAC Systems (with Air Scrubbers) but even with my bad vaping habit these Filtrete 1500s make the air in my oversized master the hospital grade at all times. Their build quality with tight-packed V's and the superior tin fencing on both sides helps us jimmy-riggers win too! Best product on market without question. **Do add a carbon layer in whatever format you like and provides value - such as cut it yourself - if you're trying to combat odors - such as cigars or real cigarettes - or worse like from kitchens, bathrooms or basements. I have had some success placing a thin, cut it myself layer of carbon lining on the exhaust side (clean air output) side of one or two of my units. Hope it helps!

Always the best. Improves the air quality.