My riding bud has one of these, seems to work well as long as you aim it right not to get 30 minutes of the guy's crack in front of you on the descent.
'91 Toyota Pickup
'09 Kawasaki KLR650
'12 Gunnar Rockhound 29
“Anyone who believes in indefinite growth in anything physical, on a physically finite planet, is either mad or an economist.” -- Kenneth E. Boulding