This option is specified for single-board computers: if you need to install a Raspberry Pi operating system .img file to your USB drive — this option is what you're looking for. To successfully install a Raspberry Pi operating system to the USB drive you need to complete the following steps:
Plug-in the SD Card.
Click the icon on the toolbar.
The following window opens. Choose the device, press Refresh if the needed one is not on the list, set the path for the needed .img file. Press Continue.
All your data will be wiped from the chosen USB drive. Make sure you've saved all the important files before you press Continue.
Once the process is finished, your SD Card contains the operating system and is ready to use.