It works great. Really easy to use. Just insert it in the valve guides and hit the back of it with an air hammer with a rounded bit. It took just a few seconds per valve guide. The layer of copper on the driving surface made it so you don't mess up the new valve guides.
In this thread I am using it in post # 75...
https://board.marlincrawler.com/index.php?topic=102500.60
