Unless you're in a band, taking a guitar on the road is difficult, so PocketStrings was created to allow guitarists to practice when bringing the real thing isn't an option.
PocketStrings isn't a miniature replica of the guitar; instead, it's built to mimic the top four frets of the neck. What's even more interesting is that no music will actually play if it's strummed. The whole idea behind PocketStrings is to simulate the feeling of making chords with the hand while building finger strength at the same time. It's a good tool for beginners who are just starting to learn the basic chords.
There are plans to release a PocketStrings model that's easier to strum, and one with six frets so that scales can be practiced on it.