There is one installed on the RTL on the showroom floor where we bought our Ridgeline. I'm glad we got to see it in person because we are not impressed.
Yes, it locks the tailgate but it looks like an insubstantial lock to me. It did not work easily with the key. Part of that is because it is a demo model and people aren't especially careful with items they don't own. I want to see durability and there was a definite lack thereof in the locking mechanism.
It is not water tight. What's the point? You have to keep everything in the bed in watertight containers?
The rigid half fold left a deep cavern that you'd have to crawl up into the bed to access anything you are hauling around.
It would take a strong person to get it out of the bed after unbolting it. Someone has posted that once it's out it's a storage problem because the edges compress from the weight. Do you have a place to store it flat? I know we don't.
I'm waiting for the roll top models to hit the market. That should be in a couple of weeks, according to Retrax.