Hi. I've never heard of it, and frankly it reminds me of the head of Darth Vader

. I looked at the first two links you have. It is an underwater filter, which means it will take up space in your tank. Just curious, but why would you consider a filter that's rated for less than the size of your tank (I think I read the biggest one was for a tank up to 15 gallons and you said yours was 20 gallons).
When getting a filter for a turtle tank, think more powerful rather than less--they are much messier than fish. Ideally, you want a filter that's rated for at least 3X the size of your tank. A 20-gallon tank limits your options. If I were you, since your turtle is already 2 inches (this is the shell from the scute behind the head down the back to the tail without the curve?) and will grow, the tank size is already at the limit for his size (think 10 gallons of tank per inch of shell length), I'd look into upgrading his tank size and then get a filter appropriate for that one.