Believe it or not, we had a hard time finding a source for this particular wire brush. The bristles are just the right stiffness for removing the solder flux after you have finished soldering a turnout - not too stiff that it damages the trackwork, but stiff enough to effectively clean the track.
Stainless steel bristles are mounted into a wooden handle that is 8" long. A single brush will last for about a dozen turnouts. Be sure to check out the video to see just how well it works.