The trouble is that the bolts that come with it are too long, and they want you to install a jamb nut with them. This is just a dumb design, in my opinion, because the bolt heads stick so far out of the back that when you attempt to adjust the beam as high as it'll go, the bolts are pointed downwards and they hit the mounting surface before the beams are level.
I'll have to take pictures of my install of the shorter bar. The jamb nuts make the entire thing a breeze to adjust up or down. The only side effect is that you have roughly, one-half inch gap between the light bar and the supplied brackets. To adjust tilt: I loosen the jamb nuts maybe 1/8 turn, rotate the bar, tighten the jamb nuts finger tight to hold the whole thing in place. Tightening a hair more with whatever pair of pliers or wrench I have on hand.