It's rated for about ~600gph. Anything above that works, but it will use up the roll very quickly.
basically the idea is when the fleece get clogged, the trapped water will force the roller to spin, rolling the dirty fleece up. The dirty part stays above the water line so it won't break down any further. In the end, just take out the dirty roll and hook on a new one.
They are ideal for smaller tanks. I have mined connected to a Jebao DC pump. It sits in its own sump section right after the filter socks. My idea is any detritus that goes out of the socks get trapped in the Rollermat section, with minimal amount crossing over to the next section, which is the skimmer. And if i go on vacation, I will remove the filter socks and leave the roller on.