Knocked off one star for the assembly instructions posted on this site, which must be for a previous version of the tray. Newer instructions were not included with the product, either. Seriously, printing a few pages of the updated assembly and including it with the package is dirt cheap, and would have prevented some frustration here.
Problem is that the parts I received were somewhat different from what is shown here or in the PDF instructions, affecting how it had to be put together. The hinges were pre-assembled (not a problem, good in fact) but required metal tabs used to align on the profile channel to be inserted in the hinge faceplate — not the easiest to pound into the holes because the hinges were powder-coated and made for a tight fit. One of the hinges is shown mounted on the end of one of the crossbar profiles, but none of the four supplied had a drilled/tapped hole for the M8 screw to go into. Had to mount the hinge on the side which used a slot nut, so I was now one short (no extras were supplied). Since this was to be mounted on a different brand of rig, who provided plenty of extra parts, I didn't have a problem there.
Once assembled, it works well enough — though the bottom of the tray scraped the top of the crossbars/hinges, so I had to add a couple washers to space the tray up a little. All in all, it is exactly what I was looking for — it swings in place comfortably, and goes well out of the way to get out of the rig easily.