Don’t think about Professional Charging 2 USB
I bought the small one so I could use it on my cats and medium-sized dog. It works pretty well on the cats, but my dog has coarse, thick hair (Corgi), and I have a difficult time getting it through to the skin. The blades are the same on all sizes, so the size isn’t the problem. It works okay, but because the blades are short and close together, I have to press hard to get it through her coat. It seems to pull and hurt her a little, so I stopped using it on her. I found a different product yesterday for her–Oster makes one called ShedZilla that has longer, wider, and safely blunted blades that easily go through even her hair, AND she seemed to enjoy it! So if your pet has this kind of hair, the FURminator might not work as well as you hoped. It is pretty good for shorter, thinner, or finer coats though.
Professional Charging USB 2