Media filter pads are a great product for residential use but for some reason is more commonly used in commercial applications. Because of its relatively low cost compared to some other types of disposable air filters it is a good alternative to pleated air filters and cheaper disposable types that are not efficient and do a poor job.
Air filter media is pre-cut to the dimensions you require and is installed in a permanent filter frame that fits into your furnace just like any panel type disposable furnace filter. Filter media can also be bought in rolls and cut to size; this is for commercial applications where large quantities of filters are changed on a regular basis.
This type of air filter media is also very efficient and effective at trapping mold spores, pollen, dust, pet dander and many other airborne contaminants. The standard disposable panel filters that you can get at your local hardware store are not even close to being this efficient. This type of filter seems to last forever and never get dirty. This is because most airborne contaminants just pass right through.
Some pleated air filters are almost as efficient as media air filters but you have to be more cautious about how often you change them. These filters do not have as much holding capacity as media air filters because all of the dust they stop collects on the surface of the filter. This leads to greater airflow restrictions over a shorter period of time.