I hadn't realised that this was such a tiny product when I ordered it, but then that's my own fault for not reading the description thoroughly (it does state that it comes with a key ring, after all). The main body is about 45 x 45 x 20 mm, so it's certainly portable. Unfortunately, and perhaps by necessity, the high carbon steel tape isn't rigid at all and sags under its own weight as soon as it is retracted. I can see that making it difficult to use in certain situations as it requires two hands to use it - one to hold the case and the other to support the end of the tape itself.
It's probably most useful for measuring the length of short objects, rather than distances.