Works well as a tuner. One interesting thing, when you unlock the locking mechanism, the way for the string looks blocked. This is fine, as a little ball is held in place by a string, which you can easily push out of the way with the string. This probably is less likely to over-squeeze the string.
However installing it is not straight forward. It fits in the standard 10mm hole, but to install it you need 2 precise, small holes for the positioning pins on it. This is not the best design IMO, as it's hard to install, and in case you previously had a tuner with the little "leg" and screw, it will leave that screw-hole exposed.