Lee's 5-1/2 Premium Undergravel Filter, 8-Inch by 16-Inch

It does it’s purpose, don’t know the difference from the other.

This product is great it keeps the water really clear. Buy yourself an algae eater or two to help clean debris from the bottom of the tank and you'll have crystal clear water. If you only have a betta fish in the tank it seems to me that unless you can vary the air pressure, the bubbles would stir up a lot of water because this filter is efficient and circulates a lot of water. Or other tropical fish I think it would be fine. If you're the aquarium enthusiast that likes still water this is not for you. Oh and by the way you're going to need a powerful airpump...so if your pump is small or on the way out it's a good idea to buy a new one while you're here on Amazon.

Not bad but you need pumps

We were having issues with our 13.5 gal oddly shaped tank and keeping the water clear, and the fish healthy. I ended up pulling the fish out, lightly cleaning the gravel and ornaments & adding this UGF. It has made a great difference - three weeks in, and the water is staying nice and clear. I can see it pulling the small food particles through the gravel when the fish do not consume them. Very happy, thank you Lee's!

I bought this for my 5.5 gal aquarium and fits perfectly. It was easy to install and it actually makes me look like I'm an aquarist. My water is super clear and my fish are happy. I use this along with my mechanical filtration. Remember that if you have a brand new aquarium you will have to give it time (cycling). It took my aquarium almost 2 months to stabilize so be patient. Here is a picture of my aquarium.

Use a water pump at one end up lift and a siphon at the other end up lift to thoroughly clean once a year.

Not even close the size listed. Says it's 8×16. In actuality it is 6 1/2×14.

The carbon heads are kinda worthless but I use power heads and it works super. I like this design better then the flat ones , the channels give more area for filtering.