I have them in my Avalon,and have done for about 6 years now.I wouldn't be without them.Having said that,they don't seem to work with my Martin MC 16.Perhaps it's the wood ??----the Martin is spruce,the Avalon cedar.Whatever the case,I prefer the sound of the Avalon ! I have them also in my Samick 12-string,and that works,too.But they need polishing regularly---every time I change strings(which is often) out comes the Brasso !