Needed a new filter for my cooker hood but with it being an older one (Blanco) wasn't sure which make/size to go for. With these filters being universal it did away with me having to get the exact size right (so a god send for most people).
You get two in a pack and just simply cut to the size you need (quite a bit left over both length wise and width wise with mine). When it needs replacing you have it turn pink so you can see at a jiffy. That said though no instructions were given as to which side up or down in goes in (could be a good idea if makers put a marking on for the item to show which side nearest the hob it should go, simply a case of common sense you may say, but if you haven't changed one before (like myself) you won't know.
For the price including the free postage a real saving on those down at the local electrical store and they do work.
I was also impressed with how quickly it was dispatched to me, ordered one day (in afternoon) delivered the morning after that.