Top positive review
Very good for the money, instructions could be better, resolution to +/- 5 cents.
September 20, 2017
I did some testing with a high accuracy frequency source generating a sine wave and found the resolution to be about 5-6 cents. In other words, your tuning could be out by 4 cents and this tuner will still indicate you are in tune. This is fine for casual practice, but if you are doing studio/recording work you will likely want your tuning to better than 2 cents. I only have one unit to test, so your results may be different.
----------- Original review
This is a basic tuner that works by vibration only (it doesn't have a microphone), nor does it have any extra features such as a metronome. It came with a CR2032 battery and a minimal instruction sheet in English and Chinese. I already have a Snark ST-2 which I like a lot, but figured I would try a less expensive option for a spare guitar that I leave in another room.
The accuracy seemed good. I tried it on a couple of electric guitars and it matched the snark for the most part, however the snark seemed to have slightly better resolution (this tuner would indicate the string was in tune over a wider range than the snark). It's very easy to operate, just depress the button on the side for about a second and it comes on and is ready to go. The display is bright and easy to read and turns green when the note is in tune. The illumination is bit uneven being brighter near the top, no big deal. It automatically shuts off after 2.5 minutes, or can be manually shut off by pressing the button until the display goes dark. Responsiveness is reasonable, the snark is slightly faster, but I had no trouble using this one.
The instructions indicate it is adjustable: an A4 note of 430-450hz, HOWEVER I didn't figure out how to change it from anything other than a standard 440 A. In playing with it, I did discover it has different instrument modes.
Across the bottom right of the screen, there are letters to indicate the mode: c, g, b, v, u. I'm guessing that c = chromatic/generic, g = guitar, b = bass, v = violin, u = ukulele. For stringed instruments, it displays the string number when plucked. If the mode is set wrong, one or more strings will be incorrectly identified. To cycle through the modes, tap the button quickly after the unit is powered on. It would have been nice if this information was in the instructions.
The construction is not as sturdy as the snark and it wouldn't handle drops as well, but at half the price there is bound to be some compromises. For a quick tune ups, this fits the bill. For those that require very high accuracy or a very sturdy design, more expensive options may be justified such as a pedal chromatic tuner.
I hope you found this review helpful.