We had a real interesting smell in the house and we were considering doing a ventilation system flush. Those are expensive. A friend of mine is an AC Tech and asked the last time I changed my filters. I cringed cause I literally had no idea. I replaced the space gard filter and added a carbon filter at the advice of an engineer friend and viola funky shell is no more. Thanks filter buy!
Sold as 16 x 25 x 4 but actually closer to 3. 5 inches in thickness making for a sloppy fit in the furnace slot I put them in. Other brands I have used are closer to 4 inch and make for a nice snug fit. Why call them 4 inch but make them fully 3/8 inch thinner?