Simple, ingenious, cheap, supremely effective; perfect.
It works so well it has now become a staple on all my Les Paul's & Les Paul-style guitars. It's very simple to fit however I gave it to my tech who knows how to work on guitars better than me(!) especially when it comes to electronics, and once fitted it straight away became indispensable. Many companies nowadays offer mini tuners, which work very well and admittedly do save a lot of space on a pedalboard, but this thing makes and type of tuner completely redundant. Oh yeah, and the battery lasts a long time too.