I was at a customer location and needing to reflash a thin client that had become unusable.  After obtaining the imaging utilities needed to write a bootable flash image to a removable USB, I only had one type of USB thumbdrive available, an 8 GB SanDisk Cruzer.
Once everything was ready to start creating the bootable image to the USB thumbdrive, the dropdown to select a target device was empty.  
Further research into the issue I came across multiple articles about the SanDisk Cruzers showing up as a "fixed disk" instead of "removable USB device".  This appears to be hard-coded into the device from a bit that is set, and there's really not a way to flip the bit to specify that it is a removable USB device (which is what the imaging utility wanted).
I went to the nearest big-box store, ignored 90% of their selection which were SanDisk Cruzers, and purchased the cheapest, most generic USB thumbdrive they had.  It worked with the imaging utility without a single problem and was detected as a removable USB device.