This tuner works great, probably the best clip-on I have used.
The biggest difference between this tuner and the "unitune" version, is the fact this one can in theory, tune all strings at the same time. Such a feature does not work for bass guitars, as stated ONLY in the manual, I didn't see it anywhere else. So, for a bass guitar, this is just a more expensive version of the unitune.
Other than that, this is the only clip-on tuner I could use so far capable of properly tuning a B string