Aluminum cross tube fits through the pocket on the end of your tarp, attaches to 90 degree elbows that either fit in, or are welded to, your system's upper arms, and pulls your tarp to the back of your truck or trailer. Slightly elliptical tube measures 2 1/8" x 2 1/8" x 95", with a 7/8" hole drilled 3/4" from both ends on both sides. This cross tube does not fit Aero systems.