Bought and installed two of these, straddling the garage door opener in my garage that has approximately 9 foot ceilings. I used only one vertical angle iron piece per corner, thereby realizing the minimum 22\" height (without shortening the angle irons) in order to allow clearance for my Ram 1500 4x4 we keep in the garage. This allows less than 2 inches clearance and the truck roof antenna actually would not clear if the racks were not lined up the way I have them. These are great for getting things like drop cloths, rolled roofing, painting supplies, etc. off the floor, freeing up space below them. I only had to use one large toggle bolt on one of the corners since there was no joist available. I'm nowhere near the 600 pound rating for either rack, so that shouldn't cause any issues. These are solid as a rock and highly recommended.
Aaron 
