I have no idea what the name was but i bogh a bulk pack that was flat sheet sof poly stuff like half inch thick. I Have just a fluval 404 on my 75, so i cut the sheets into even pieces that fit in the top basket. The top lid kinda squishes the pad where the seam is but it works great.
In the lid where the seam is gets really nasty cause i have a messy turtle, just pull it out and wash it when my flow is down a little. After enough washings it starts to fall apart and i put a new one it.
Fluval makes thicker ones that fit in each side of the baskets but they want a lot more money.