I was pleasantly surprised at how easy the rack installed on my truck. The only thing that was a bit hazy was which clamps should be fitted with the lock. Both front, both rear, opposite sides, I put both of mine on the front and after giving some thought switched to one front, one back, same sides. The other slight inconvenience for an older person is the numbers on the uprights are very hard to see with black embossed on black. So far it has easily held 12 ft 2 x 4's. 10 ft plastic pipe.
Great rack for the price
They were easy to install very sturdy and lots of places for tie downs. I think they will hold more than 500lbs based on the design however I have no need to try they are for my staging and it comes in at less than 500lbs which is the reason I bought them. Look great on the truck too!