Why buy a separate tuner to take around with you when you already have your pc or tablet with you that can do the job. In fact it can probably do the job better than most cheap tuners on the market.
Tune Up helps you tune any instrument. it works by finding the note nearest to what is heard, and then shows how flat or sharp it is using a needle on the screen, as well as how many percent of a semitone (cents) the note is off center.
Tune Up is a chromatic tuner, which means that you can tune to any note, not just particular ones. This is a great help for getting high notes in tune on wind instruments.
If you are using a transposing instrument, you can also select its key, for example a Trumpet, Clarinet, or Saxophone. For guitar, piano, flute, etc., choose the key of C.
If you are playing a guitar, choose the key of C, and the neck of a guitar is shown where you can play tuning notes for each string as well.