Roof rack. I aligned holes in the bar to existing risers and holes on my Aluminess roof rack. As mentioned by others, theft deterrent, rarity of use, etc. I used to store one on the front grill guard of my pickup, but the winter was hard on it there, catching all the grit on Colorado roads (summer and winter). When I did have to use it, it was so froze up with grit and rust, unseizing it was a job of it's own!
2009 E-350 Lopes 55