The size breakdown must each according to personal needs look, however, the product description is not 100% accurate (you could tell because there instead of 31 only 30 parts are listed - except the bit holder counts for 2). The correct list of bits can be found in the 3-star rating.
For a bissl more money you get reasonable quality here. Who regularly requires only 1.2 or 3 bit sizes, the need to buy a set. As my individual bits but regularly disappear, this time I wanted to have a box for storage. And at some point you need sometimes a not so usual size.