Use if for my signing business and absolutely love the dual tray since my documents are both legal and letter. The dual tray makes it perfect! I never give "5 Star" ratings as I always believe there is room for improvement. But I love the dual tray!
We use quite a bit of legal size paper for church bulletins. I wanted an extra drawer for our printer that would hold legal size paper, so that I wouldn't have to keep loading and unloading the main paper tray (that holds the letter size paper) or have to use the bypass tray every time I needed to print legal size.
This extra drawer will hold legal size paper. You just won't be able to close it all the way. The drawer sticks out about 3" from the front of the machine. (You can close the drawer all the way if you load it with letter size paper; and I would fully recommend this feeder tray if that is what you want it for.)
It will still print just fine - since the printer pulls the paper from the back of the machine. It just looks dumb with the drawer open all the time (letting in dust etc.) This isn't the fault of the feeder tray. It is the printer that has a flawed design.
So if you are looking to purchase this extra feeder tray so that you can use it for legal size paper with your HP Color Laser Jet Pro MFP M477fdw, you might want to keep looking around for printers that are better designed.
I unboxed it, put the printer on top (M452dn), through the web interface to the printer I set the various paper sizes and types for the different input trays, loaded paper and have printed flawlessly since.