Manufacturers are making smaller USB flash drives, which is a good thing and a bad thing, experts say. The good news is that the smallest models stick out no more than one-quarter of an inch when they’re plugged into a computer. That means that the USB flash drive is less likely to get knocked out of the port. But the bad news is that the smallest models are easier to lose or misplace. In other words, the miniaturization of USB flash drives could be described as magic: Now you see them; now you don’t.