This contact microphone is great. The sound quality is excellent, and so is the build quality. Apparently it's a miniature condenser, so that would explain why it beats all the piezo type contact microphones I've tried. I've had many of these attached guitars, violins and kanteles for years, and they all work well even after extensive recording and playing live. The microphone requires a dedicated preamp/power supply from AKG (B23L or B29L) to work, and with that you can get plenty of amplification even with a really quiet instrument (for example, the kantele). I'm also really happy about how well the adhesive putty holds. The microphones I've installed have stayed attached perfectly for over half a dozen years without coming loose at all. The adhesive is easy to remove when needed too, and doesn't stain the instrument. I recommend this microphone wholeheartedly for acoustic instruments.