Tunze 9004 Protein Skimmer rated for 15 to 65 gallons. It fit great in the back of our Waterbox AIO tank, we upgraded to a larger skimmer and no longer need this one. It is missing the magnets for the outside of the tank, but you can easily replace with other magnets, we had it just sitting in the back of the tank without using the magnets at all. It has been used for 9 months, it has been sitting out for 1 of those months so any hitchhikers are long since dead. The last photo is of the mini feather duster shells left over, they can be scraped off if you want, but likely this will never be seen if it’s in the sump or back of an AIO. Retails for $189 on Amazon, priced to sell at $100. First come, first served, if this list is still up, the skimmer is still available. Thank you!