I haven’t changed the air filter in my brand-new HVAC unit, since I had it installed four months ago. I know that’s awful for the HVAC unit, but I keep forgetting to change the air filter. The sporadic beeping red light on the thermostat, finally prompted me to investigate the problem. When I finally decided to change the air filter, I couldn’t find a size printed on the flimsy piece of cardboard. It seemed like a very good brand, but I couldn’t find a size measurement anywhere on the air filter. I had to find a tape measure, which was located in the back of the tool shed. I had to move the lawn mower, a box of old tools, and several pieces of old cable, before I could get to the measuring tape. My air filter was 23 in Long by 20 in wide. It seemed like a very strange size, but my son confirmed the air filter size on the internet. I went to the local Supercenter to purchase some chocolate milk, oreo cookies, two new pillows, and the new air filter. They had a pretty large selection of air filters, but I didn’t find a single one that was 23 in wide. I didn’t know what to do, but I decided to purchase a slightly smaller air filter. I didn’t want to go any longer without changing it, since I had forgotten for so long. The air filter isn’t the right size, so I will need to special order it next time. For now, it seems to fit the shaft enough to filter the air.