Daddario PW-CT-14 Micro Violin Tuner

The clip-on mechanism feels a bit awkward at first, but actually works really well. Just clamp it onto the upper bout of the violin, and flick the lever. Easy to attach and remove with one hand once you get used to it.

I suppose one could technically keep it there at all times, as it's not getting in the way or anything, but strangely, I find that it slightly reduces the mid range resonance of my violins. I did not expect that to be audible, considering that the device weighs next to nothing, but well, violins are sensitive instruments...

It is easy to apply and works not only as a tuner but also as a live-tuner, which gives you instantly feedback if you are in tune while you are playing. This is very useful for beginners, also while trying to interpret notes if one is not use to where the different tones are located on the violin.

The only negative thing is that the batteries could have lasted longer. Even if there is a screensaver function built-in.

Just costs more depending on the clamp, so you'll get punished differently depending on what you're playing. The (violin) clamp is OK, not super sturdy and can slip off my instrument, but the tuner itself is very good and discrete (looking at you headstock clip-on guys), and you can quite easily pretend to have perfect pitch when tuning. Readout is great and can be flipped in all orientations, and the measurement is spot on.