Chrome Recovery Utility Extension

Click here to visit a Chrome OS Flex Help page that mentions the use of this Chrome browser extension for creating 'Flex' bootable media.

N.B.

It's worth noting that there is an option that can be used post installation to erase the 'Flex' image entirely from the USB [as other OS's like Windows do not always recognise all kinds of disc partitions] and this could be useful for recovering any USB media that appears to have shrunk in capacity / or become unusable, leaving the USB reset to it's total available storage size.