I have the Greddy weight round knob w/ a Karboy SS. The knob is awesome. I can feel all my shifts better (more solid than my MOMO) and definitely worth the price. The weighted knob makes shifting easier and faster IMO. Only bad things are that it doesn't mate the shift boot and is really short combined w/ a short throw shifter. The Kartboy is very similar to the Greddy knob, but IMO I think the Greddy knob looks a lot better.