what tool do I need to adjust Litronics height?
 

I want to lower the height of my Litronics so that I'm not lighting up trees, houses and blinding oncoming traffic. I read in the manual where it says adjust with a hex socket wrench left or right.
I don't have a long set of allen/hex wrenches, just short ones that don't reach. What size allen wrench do I need to adjust the height of these lights?