There are two sizes that look the same so be sure to do your homework and buy the one to fit your machine. The model number is on your electrolux machine, on a label stuck to the body. I ordered the right one, it fits and gives new life to the machine.
TOP TIP: The foam filter protects the fabric filter in the black plastic and rubber mounting it is fixed to, so buy 2 foam filters and SWAP them over regularly. (weekly?). Take the dirty filter wash it thoroughly and dry it in the airing cupboard, ready for next weeks SWAP. Clean foam keeps the vacuum at maximum, and protects the fabric filter.
I struggled to find this product that I thought would fit my old but trusty and still working vacuum. I feel it is expensive for a bit of foam that was too big and i had to cut down which meant the slit was then in the wrong place. It will have to do but I don't think there is the correct size one out there.