Submersible filter

[PumaWard]

I have this old (about 7 years) submersible filter, but I have no idea what tank size it's rated for and I can't find any information on the internet for it. This is what I got for information off the filter itself:

UL Minigon II
Model # PF-311

I've added it do my 75 to help the whisper with filtration... any info on it is appreciated.
Thanks.