A-F 0-9 8 digit mask Help

[mysterdee]

Could somebody please explain to me how to generate a 8 digit mask using 

UPPER A-F 0-9 (8 digits) MASk

i have currently tried -m 2500 -a 3 -1 ?u?d ?1?1?1?1?1?1?1?1  and got a 2yr time

im hoping to shorten this with a correct mask that uses 8 characters instead of itterating throu 1 character to 8 in increments

Anybody help me.

8 digit mask A-F 0-9  for wpa password i.e (AF12FE55)

thanks in advance