I received one of these, had to return it, then received another with the same problem. Each time the vice came with two copies of the same collet (the metal jaws that hold the pin, wire or bit). So rather than four sizes ranging from tiny to fat, I could only use two sizes, the smallest and the largest, but the vice could not hold anything of an intermediate size. The pins I am using (c. 0.9mm) could not be inserted into the small end, and fell right out of the fat end, even when tight.
The packaging the vice came in, both times, appeared to have room for another collet on display, but instead the second collet was already housed in the vice. I wonder if this is significant.
Either way, clearly some purchasers have received the full kit, but it seems at least one batch of these devices have this issue. If you happen to be working only with thin wire, or fat drill bits, you won't care. If you want this to hold pins or needles or thicker gauge wire, then this will not work for you.