The top of this rack is completely flat to transport large objects such as lumber, canoes, roof top tents, etc. We call this rack "UTility" for all the different applications it can handle.If garage height is a concern, this rack is the best option. The installation is done directly to the body frame without drilling, the outside frame is made of 1 inch tubing and the flooring with inch cold roll steel tubing. This rack was designed around the 4 factory mounting positions on the roof of the vehicle and also was designed without sunroof cutout, there is a cutoff on the floor of the rack to avoid interference with the roof antenna. No drilling required for the installation.