There are just somethings a homeowner just won’t know how to do. A furnace tune up is one of those. It is required by the manufacturer’s warranty that only a certified technician does the tune up for reasons like the testimonial below. A homeowner was using a filter that she thought was fine for her system. It turns out that particular filter was causing damage to her blower motor. If this tune up was ignored and she kept using the wrong filters she would have had a way larger repair on her hands. Thankfully the furnace technician caught the problem before it escalated safed the homeowner a lot of time and money.
You should check with your local technician, the products themselves just list the sizes and tell you what size machine they can go in, but like the story above there may be certain ones you want to stay away from. If you have a reusable one talk to your local furnace technician before using.
Filters need to be changed whenever they are dirty or every 3-4 months whatever comes first. If your furnace filter is dirty often it might need to be changed more often. I always double check my furnace filter one time a month to make sure there’s not large visible debris, if it looks good I put it back in, if it doesn’t look so good I change it out right away.