RB-1006-49 roof crossbars attach to your vehicle's side rails, allowing you to carry luggage, cargo, or other gear on your roof. These sturdy roof bars are constructed of carbon steel and can carry up to 150 lbs The roof rack crossbars include adjustable clamps to fit various side rail spans and widths. The clamps slide along the crossbar to accommodate side rail spans of 33.5" to 45" and easily adjust with the turn knobs to fit side rails from 1" to 2.25" wide. The roof bars must be placed at least 28.5" apart for proper balance, and the top of the vehicle roof to the top of the side rails should be at least 2". Each crossbar features an integrated lock to keep it secure. RB-1006 crossbars include a one year warranty.