Hallo 
Im looking to upgrade the firmware and ive been looking round to try and see if i can find out which drive i have but no luck as of yet.
in device manager it shows as:
BENQ DVD DD DW 1620
and using the fwcheck program from benq’s site it says i am using firmware:
B7V9
Can anyone help me?
Just upgrade to B7W9 if you want the last firmware released for 1620 drives. Though I have read that it is possible to use firmware for the 1625 drive aswell but have never had the desire to try, B7W9 is excellent for my needs. 
No difference in hardware from 1620 to 1620 PRO.
I was thinking it was B7L9(?) that made the change to Pro? My old brain could be wrong 
All I can recall about B7L9 is that this is some sort of eeprom “cleaning” firmware.
But then, maybe I’m just too jung to know. 
Well then maybe it was B7M9 