I'm not positive, but I think the electrostatic filters are supposed to give you the filtering of the pleated, without the reduced air flow that pleated results in. Those spun fiberglass filters are all but useless for reducing dust in the house. But that's it right there - if you don't have an issue with dust, why filter out what doesn't need to be filtered? Just a couple weeks ago, I finally convinced my wife to just put a box fan in our central room of the house, and leave it running - I placed a pleated filter behind it. The air flow (pressure difference + friction) holds it in place. After just a week, my wife was amazed at how much dust it captured; the filter is filthy. (Some remodeling work going on; lots of dust had been created.) And, my wife is commenting on how much less dust is on the furniture. It didn't have to be changed, but she already went out and bought 3 or 4 more filters, and changed the filter. I'm planning on testing out the electrostatic filters once summer rolls around and more air circulation would be nice.