The best pre filters out there. I cut mine shorter but other than that it’s a perfect tight fit on the filter outtake, making maintenance on the main filter much easier.
I have added the large pre filter sponges to all my large HOB filters. The fit perfectly and help keep the HOBs clean.
I bought this large prefilter for my penguin 350 as anyone with a penguin knows it's hard to find a prefilter for the 350 because of the rectangular intake but this prefilter worked perfect for the 350 and it's course enough to where the water is not restricted and the bio wheels still turn absolutely recommend this product