Other Thoughts: This brush is amazing on sandstone. The best climbers in the US and Canada use it. But it wears quickly. So, just like your newest, best pair of climbing shoes, use it at the peak of the season or on your hardest boulder problems.. There are less than a few hundred of these brushes left in the country at the moment (August 2007). The manufacturer has stopped distributing them in the US, yet they cost more ($8+) in Europe.