Ignore 'case' of input when comparing

I have a batch where i have to test a variable against a two letter user input and i need it to proceed regardless of the "Case" if the letter as long as they match
if %var" = the input of aa or AA or even aA I need the comparison to ignore the 'case' of the letters, I thought this was done with a /I but I am to tired to look further and I must be doing it wrong. Past my bedtime

Thanks

Something along the line of this test batch file ?

Code:

@ECHO enter aa or AA or any combination thereof
@ECHO OFF
@SET /p VAR=
IF /I %VAR%==aa (
ECHO  --------------This input works OK---------------------
pause
exit
)
ECHO  --------------This input doesn't work-----------------
pause
exit