All of my RC 1/10 cars are now using Kawada pinions. Huge range, in rcmart, to choose from, which is very convenient. Also the quality of the gears are very good, almost the same as the Yokomo gears but cheaper.
As the last review said - these pinions are indeed the best! I've been running Kawada pinions and spur gears in my car for ages and they last and last and last! I swear by then now and recommend them to everyone!
The manufacturing quality of these gears really is second to none. They are very precisely engineered as easily meet or exceed the quality of any other gears I have run in the past.
I also like the fact that they are clearly marked with the number of teeth - this makes them easier to indentify and ensure you are running a good ratio for the track conditions.
The only reason I buy more now is to give me different gearing options for different track conditions - although it's always good to carry a couple of spares of your favourite gear combination as it's not good to have..