This is one of the worst purchases I've made on Amazon (I've made a lot of purchases on Amazon, monthly). To start, I was super addiment about paying this much ($42.49 2-pack) for a 16x20x4, but it was cheaper than the big box store and the reviews were great! I knew that this one was slightly less in size than the stock size of 16x20x4 but I didn't realize how much trouble that would cause once installed into the furnace. Since this item is a little smaller in the dimensions, it moves quite a bit in the furnace box, so much so, that return air (and dust) can just go around the filter. Lastly this item is SO CHEAPLY made. I mean really bad. The pleats are badly glued to the carboard enclosure, loose and not evenly spaced. Lets just say, I'm never buying a product from this brand again. We really should not have to be paying this much for a cardboard and fabric filter. That's it!