TC's innovative Polytune pedals are designed to make guitar tuning quicker by dispensing with the need to carefully pluck each string individually when tuning. I have both the original TC Electronic Polytune and Polytune Mini, but although the full-sized version always worked fine, the Mini never really seemed to get its act together when used in Poly mode, and I only found it useful as a basic one-string-at-a-time tuner.
TC are now part of the Music Group and this MkIII version of the Polytune Mini is designed in Denmark and built in China. More importantly, it's a huge improvement; right away the Poly mode delivers a solid readout, showing which strings are in tune, sharp or flat. And you just need to strum across all six strings for the display to switch automatically to Poly mode. Furthermore, TC have done what I've been nagging tuner manufacturers to do for years: build in a good-quality buffer for your pedalboard. This makes perfect sense, as the tuner is almost always placed at the start of your pedal chain, right where your buffer normally goes — unless you have one of those super-picky germanium transistor fuzz pedals that don't like buffers, that is! They've also added a pair of miniature switches, one to bypass the buffer if you don't need it, and one to leave the tuner display always on if you prefer it that way. The buffer circuit, which has a 1MΩ input impedance and the ability to drive long cables, is based on TC's very quiet Bonafide buffer pedal circuit, which I've used myself and know to sound very transparent.
TC have done what I've been nagging tuner manufacturers to do for years: build in a good quality buffer for your pedalboard.
In single-string mode, which is selected automatically if playing only one string, the display includes a strobe pattern that moves to the left if the note is flat and to the right if it's sharp. Get it to stay still, and you're in tune within ±0.02 cents. The display has also been fitted with extra-bright LEDs for better visibility in bright light. Using the footswitch mutes the output while tuning, and in standard mode extinguishes the display when you are not in tune mode. There's a three-year warranty programme if the product is registered within 90 days of purchase, and a 'dark' version is available in black if you prefer that to the standard white version.
Given its affordable price and compact format, the Mini is the perfect choice if you have a pedalboard that can provide it with the 9V supply it needs. (As with the vast majority of miniature pedals, there's no internal space for a battery). If you don't run a pedalboard, then the full-size version may suit you better, as that can be run either from a battery or an external power source.