Just binned mine. Got it as a fan/filter combo on fleabay.
It just didn't work very well/at all for me. Could still smell my grow outside the house with it running, had to buy a proper filter in the end.
I was going to keep it and use it over the end of my inlet to stop bugs n beastie's getting in but it actually stunk my room out of my last grow when I turned it on!!!!
So it's actually more then useless

and it went in the bin.
Do a search for "125mm filter" on ebay there is a guy doing them for £35 which is pretty cheap and they work. He WAS doing them at £24.99 on special offer so keep an eye out for his offers. They use a green bckground for there pics, not allowed to give direct links but you should find it from that info.