I also use the Chris Christensen Gold series 27mm pin brush. Do a search on google for it. It is well worth the money, especially on silk coated yorkies although I use it on all of mine. When I first looked at it, it looked like brushes I had seen everywhere but the other brushes were cheaper. So I have tried just about everything before I finally broke down and got the CC brush. It was everything they say it is and more. I love it.
Here is a link
http://www.chrissystems.com/brushes.htm