Foam rubber was about 1 cm shorter than the original. To use it I have to place it on the device and hold it short, covering the vents but not all the way to the bottom. As the foam ages and expands, this no longer works as the foam will slide down and no longer block all the air holes. After a few months of use - the foam has unpacked from the box and fits perfectly! It was so nice to be able to turn off the dirty filters and continue cleaning.