For 2 door vehicles and pickup trucks, it may be necessary to use the Q Stretch Kit to achieve a functional bar spread between the front crossbar and the back crossbar. Each crossbar needs to be mounted in the doors. In a 2 door vehicle, there is only approximately 8" - 12" of usable space at the top of the door-frame, which would yield a very narrow crossbar spread. By using the Stretch Kit, you can mount a 2nd crossbar up to 30" behind the first crossbar. The system still mounts in 2 spots on the top of the door-frame, but with magic, extends the 2nd crossbar back further on the roof.