So while walking through my local thrift shop I came across these. A us aquarium inc, and an Amiracle acrylic wet dry style filter. I've never used or seen these before but they have attachments for HOB use but I can't find any information about these. Mainly how is the water supposed to enter the box if they are HOB. The hanging apparatus on the Amiracle are hollow and I can follow the predicted path for the water but the US aquarium is just a box and appears to have a skimmer collection cup that just rests on built in cylinder inside the box. I paid 13$ for them both and figured it was worth a gamble.