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 Pickup - Imelda
'08 Tacoma TRD
'09 Kawasaki KLR650
'12 Gunnar Rockhound 29
"To live is to suffer, to survive is to find some meaning in the suffering." -- Friedrich Nietzsche