Designed for the EF 28 - 135 lens, and you can tell. Fits well, turn to a click, with markers than line up to show it has not come loose. Nice size to it, pretty big. I have had no issues at all with this hood, does the job it was meant for.
I am sure it is better quality that many copies out there and would not consider using my 28 - 135 (which is a nice lens) without it.
I could not possibly give this 5 stars though, as for what is basically just a piece of moulded plastic, it is too expensive. I know anything that says Canon on it usually is, but it could surely be made and sold with profit at a lower price.