|NOT guaranteed to be 100% accurate in all situations.|
USE AT YOUR OWN RISK.
All this does is check if the mounted drive has the text
"RemovableMedia" as part of it's registry entry.
for /f "tokens=2 delims=\ " %%a in ('
reg query hklm\system\mounteddevices /s ^|find "520065006D006F007600610062006C0065004D0065006400690061" ^|find ":"
') do (
if exist %%a\ echo %%a is removable!