Well, what foot sizes are large/medium/xlarge etc...? Also, how do they compare to more expensive fins? How do they perform while scuba diving?
I don't know the exact foot sizes but I know they run a little large; I would normally get medium and I bought a small. However, I ended up returning these fins because I was told by an expert that they are lightweight fins, which are for snorkeling. While they might work, you might tire out fast.
The size is mostly the same as other fins, the ones we bought were for my wife and they were a small and they fit fine and she wears a size 8 shoe. as far as performance they are somewhat different from the top quality ones but were still fine, especially considering the price.
These are excellent fins. I wear a size 10 boot and originally ordered the Large sized fins, but they wouldn't fit on account of the 7mm boots. So I exchanged them for XL. They fit nicely and are very comfy underwater. I even got spring straps but am happy with the rubber straps that came with the fins. So I keep the springs as spares. Good propulsion with all kinds of finning techniques.
It appears that you are an inexperienced diver so I will give you some basic advice. Diving equipment is very personal and what is good for me may not be for you. As far as fins go I prefer solid rubber as opposed to plastic rubber plastic as these can delaminate and if stored improperly can retain their bent shape. Some people get leg cramps if the fins are too stiff, however, softer fins are not as fast. In my opinion a medium stifness solid rubber would be your best bet. Scubapro makes a good split fin, black, that seems to work for most people bit I prefer Tusa. 6-10 medium