I use mine for practicing sight-reading. They are fantastic. Very, very transparent - by this I mean that if you have ANY string noise, it will come through. They teach you to be much more careful in your technique, and because you can hear *everything* (and quite loudly, I might add - it is pure acoustic conduction, no volume control) you tend to play a little more softly than you might otherwise practicing unplugged, or even though an amp. As a result, technique improves. I highly recommend them - just got one for the guitarist of my trio, too.